Actually, Yangon nightlife has come a long way in the past few years, so an evening there would be good.
Scores of new bars, restaurants, rooftop establishments, galleries, expat functions, events etc

Go to Myanmore.com, and sign up for their weekly newsletter "7 Days in Yangon"
Its a great way to get an idea of what is happening and what might be interesting for you to see while there.

Don't suppose you are there on a Friday night by chance? The Strand has a famous Friday happy hour (runs throughout the evening), as a meeting place for expats and locals, usually find some interesting types to meet and chat with.

Also, 50th Street Bar and Restaurant is something of an institution in Yangon.
The Union Bar and Grill is another that comes to mind.
Plenty of choices, but Myanmore is the best starting point.