My most recent campaign was set in the World of Greyhawk in the City of Dyvers and the surrounding Gnarley Forest. In this campaign, I did not allow the players to take good-aligned characters.
Prior to Greyhawk, I ran an extensive campaign that was set in the kingdom of Kashen, which was based in medieval Scotland. We used the rules for 2nd edition D&D, although the spell system was heavily modified to include pictish elemental magic and faery magic. The campaign ran for almost 10 years before I shelved it when the 3rd edition rules were released. It would have been a monumental task to convert everything
Greyhawk campaign
Kashen campaign