There are a handful of geisha in Tokyo still - Recently I had the chance to visit the open-day of a geisha house (geisha agency? geisha stable?) in the Kagurazaka area.

If you want to be entertained by geisha at dinner, then you'd better have deep pockets and ask someone with the right connections to make the arrangements. The concierge of a top hotel should able to make a dinner reservation at an expen$ive ryotei with a geisha performance thrown in. (The ryotei have close connections with the geisha and with the politicians and lobbyists... go figure).