If you want mega BP, try to get some of the really bad ones a lot, getting all good ones won't get you anywhere. Here are the items that can be bought with BP:

I T E M	B P
Remedy	100 BP
Enemy Lure Materia	200 BP
Right Arm	500 BP
Pre-Emptive Materia	1,000 BP
Regen Greens	2,000 BP
Speed Plus Materia	4,000 BP
Stardust	8,000 BP
Championship Belt	16,000 BP
Omnislash	32,000 BP
W-Summon Materia	64,000 BP

After getting 64,000 BP, talk to the woman behind the counter and she'll invite you to enter the special battles (but you have to of already purchased the Omnislash and W-Summon Materia). If you win all eight battles, with a Proud Clod as the final challenge, you can get the fabled Final Attack Materia (or some other items that have no use whatsoever).

Chocobo Square
Basically, Chocobo racing is needed to breed a Gold Chocobo and to get some rare Materia and accessories. To win some good items, you can either bet on Chocobo in the center of the room, or race your own to the left. Winning is simple, just hold down all of the shoulder buttons and circle, and you'll win every time in the lower ranks. When you finally get to S-rank, you can get some really good and rare items, or sell them for a ton of GP. To ensure wins in the harder races, max out your Chocobo's stats by feeding him every kind of green in the ChocoBill's stables until won't eat any more of that kind. Do that with each grass to assure your Chocobo a win every time. This is THE place to get GP. Just get to S-Class and race with a good Chocobo. You'll win every time, and you can sell the items instead of keeping them for absurd amounts of GP. Screw Wonder Square, this is where you want to go if you need some fast GP.

Ghost Square
This is just a simple hotel, but with a Halloween theme 24/7. You can find a Turtle's Paradies newsletter here, and you have to spend the night when the ropeway broke, but that's about it. If you really want to know, there's an Elixir hidden in Cloud's dresser.

Speed Square
Speed Arena could be thought of as an interactive roller coaster. Basically, after paying 10 GP, you go on a roller coaster with a gun attached. As you go (it will move automatically), you try to shoot as many targets as possible. All targets are either 30-70 points each if you shoot them down, with two exceptions. There giant UFO which is a worth a whopping 1,000, and a yellow boulder on top of the canyon wall worth an incredible 2,000 points. Shooting down these two things are absolutely essential if you want to get a good score. If you do well, you will get a good item that varies, depending on which disk you are on.

Event Square
Event Square is basically just a theater where you can get entertained. Unfortunately, the only time you get to do anything there is with your date. I won't spoil it for you, but it can be pretty funny.

Wonder Square
Wonder Square is a giant arcade that has a ton of things to play and do. First of all, the games all require Gil to play, and give you GP if you do well. There is a woman in the front whom you can buy some great stuff from (if you have enough GP).

The Exp. Plus Materia and Gil Plus Materia are definitely worth your while, they double the Exp. points and Gil that you win in battle, respectively. This is some great Materia that you should definitely try and get. The Gold Ticket is also great, it gives you a lifetime pass to the Gold Saucer, instead of having to buy it for 30,000.

The Games:

Super Dunk: 200 Gil
Gil Super Dunk just like a basketball game you find in the arcades here, you put in some money and try to make the basketball go in the basket. To score, you must hold down the circle button, and then release at the right time (a little less than a second). You get 1 GP for each basket you make, and when you miss the game ends. If you make 10 baskets in a row, you get a special mode called Double Chance. In this mode of play, every time you make another basket, your GP doubles, but if you miss it goes all the way back to 1 and the game is over. If you are really good at this game, you can make some SERIOUS GP. A tricky method I discovered to improve your odds of making a bunch in a row is using a metronome. If you have one, try a setting where it clicks every second, if not a little faster. Then, when the metronome beeps, press the circle button, and release when it beeps again. If it goes in, than the metronome is at the right speed. If it doesn't, try it again at a slightly different speed. I know this sounds odd, but once you get it at the right speed you can't miss!

Arm Wrestling Mega Sumo: 100 Gil
This is the expected game where you just repeatedly tap a button. I hate these kind of games, they make your finger hurt and involve no skill. Basically, you either pick the Sumo or the Wrestler, and than press the circle button like mad to win. You get a mere 1 GP for beating the Sumo and 2 GP for the Wrestler. Don't even bother playing this, it's a waste of time and your finger.

Wonder Catcher: 100 Gil
This is another game that involves no skill. Plop 100 Gil into the slot, and you will either get a Potion, a few GP, or nothing. This is just as worthless as the Arm Wrestling game.

Fortune Telling: 50 Gil
Although you don't get any prizes, the Fortune Telling machine can predict some interesting things that foreshadow what will happen late. You just put in 50 Gil and it will tell you your future. This will change as you progress through Final Fantasy 7, but it will say the same thing if you use it twice in the same visit, you have to get further in the actual game first for it to say something new.

3D Battler: 200 Gil
This is yet another game that is all luck. It's basically a more interesting version of rock, paper, scissors. You and you virtual opponent each pick an attack. If your attack beats the opponent's, the opponent gets a hit, and vice versa. If you pick the same move, nothing happens. The first one to 10 wins, and then a harder opponent comes out. Upper body attacks beat Lower and lost to Middles. Middle body attacks beat High and lose to Low. Lower attacks beat Mid and lose to High.

Mog House: 100 Gil
This is an easy and moderately entertaining way to earn GP, but you can only do it once. It is simple to beat, keep feeding the Mog Kupo nuts until he makes a sound that is different from the ones he was making previously. Do the same thing later and you win. After winning, talk to the guy behind you and you'll get 30 GP. After that, you can still play it, but you won't get any GP.

G Bike: 200 Gil
Does this look familiar? It should. As you already know, circle makes you attack to your right, and square makes you attack to your left. You need to protect yourself and the truck by defeating the motorcyclists as soon as possible. You can kill them in 3 ways: hitting them with your sword, repeatedly banging into them (not recommended, this hurts you too), and knocking down a motorcyclist and having another one trip over it. What you may not know is that the Orange Bikers are the dumb ones, who just drive right up to the truck and start banging into it, and the Red Bikers try to draw you away from truck so the other can hit it while you are going after him. Try to stay close to the Truck, never leave it to go after a motorcyclist when there are more behind you. If you do really well, you'll not only get some GP, but an item too.

Snow Game: 200 Gil
This should also look familiar. First off, pick your course. Then snowboard all the way to the finish, and you will be judged on three things. How many points you got (red balloons are one, blue are three, and green are five), how fast you did it, and technique (how many times you hit the walls or obstacles). Try to do well in all three by going slow enough to control your board, so you can avoid the walls and also get the balloons. If you do good on the easy, it will unlock the medium. Do good on that to unlock the hard course. Note that you can't do this game until you do it in real life. A good performance will give you some GP and an item.

Torpedo Attack: 200 Gil
This is the third mini game that you will have already played in the actual game. It is actually quite simple, if you do it right. The object is to take down the red submarine, but the mines and the yellow subs will make that goal a lot harder. There is an easy way to do it, though. As soon as the game starts, just stay right behind the red sub (by speeding up and slowing down when you have to) and just keep firing. If you do it right, it will go down in about 10 or 15 seconds. There are five levels, and each one gets a bit tougher. Unfortunately, you don't get more GP by doing the harder ones. Do well and you'll get some GP and an item.

Round Square

Does anyone besides me thing this name is funny? Round Square...okay. Anyway, this is just a Gondola Ride. Except for the date, you have to pay 10 GP to get in. Basically, you just ride around the Gold Saucer, and are treated to some cool FMVs (you have to look out the window to see them). If you come back after the date, you will see some more FMVs that weren't there before.