Once a month, OMSI hosts a child-free night where they offer snacks and beer and wine, along with interesting booths and exhibits about the science behind foods, games, gadgets, etc. You can cruise around with a glass of wine and see the current exhibits, too. Make a reservation in advance by clicking here.
OMSI After Dark is a great activity for any out-of-town guest as you will have plenty to talk about as you interact with different exhibits, plus it's a lot more memorable activity than drinking at a bar.