There is the right place to meet people. Near Staromestské namesti (Old town square). When you will go to Prague be careful from taxi drivers. For example ,there are three types of transport from airport to canter. First (cost 12Kc-crowns) by public transport, I do not recommended for traditional tourists. Secondly, yours tours operators, I recommended, it is up to 100Kc and you are sure that you will go where you want to :-). Finally Taxi drivers, which rates are very changeable, like weather in England for example...

I know some agencies which are providing accommodation in Prague. Here you are.