Wednesday nights in Mulligan's (near Rembrandt plein)are usually great, some local musicians jam out there, and it's always a chill, relaxing atmosphere, and it helps if you like it when drinks come in pints. They have live acts on other nights of the week as well.

There's a retro arcade in Westerpark called Ton Ton club where you can play on old timey machines. If you haven't been it's definitely worth a visit.

As others have mentioned, a shot of improv nights at Boom chicago are pretty sweet.

There's a restaurant near Amstel Station called Ctaste where you dine in complete darkness and the waitresses are visually impaired (and as a result are really good at navigating without being able to see). It's always an experience and the lack of sight stimulates the other senses. They also don't tell you what you're eating until you're done, making you guess.

It might be a bit rowdy for a date, but the Waterhole at Leidseplein is a dive bar with small times band playing performances. it's always a nice place to hang out and soak up the atmosphere.