Surprise birthday party (Amsterdam)

Hi Guys, I need advice! Im planning my boyfriends surprise 30th birthday party for the end of May, many friends are joining us from Ireland. I need ideas for a venue for the surprise party, I was thinking maybe a "party boat" cruise, or a nice bar that caters to groups. It cant be too pricey because of different budgets of people coming. Anyone have any good experiences of birthday parties? We are staying in the Jordaan area, so around there would be good, also the party cant get going till about 9.30 at night :) Thanks