The lounge/dining room of other players' houses for our 'private' game (my own bachelor pad being a bit 'surface-light' for such purposes) and in the pub with some tables pushed together for the club games.
How is Basement not one of the choices? Nearly 100% of all D&D games I've ever played have been in a basement, whether it was nicely finished and furnished, a dedicated game room in its own right, or 4 concrete walls and a 3x3 card table. I have to hazard a guess that I'm not the only person that plays or has played D&D in a basement.