There are many bars at hotels like Traders, Sedona, Summit Park View and many other high end hotels.
I haven't been able to find much information on nightlife in Myanmar. By nightlife I mean bars, discos, etc, and NOT those of the five-star hotel type. However I would feel irresponsible if I did not, on behalf of certain people living in Burma and who I rate as friends, ask you to reconsider your visit there at this time.
Is there anywhere in Yangoon and the other major cities where you can have a real wild time at night? The recent re-arrest of Aung San Suu Kyi on blatantly trumped up charges by the junta government (and the many other crackdowns on civil liberties that have accompanied and preceded this action) have in a very tragic way reminded the world, if a reminder was necessary, that while the Burmese government imposes a tyrannical hold on its citizens, it is still delighted to represent itself to a potential tourist market as a model Asian community, and as the arrested Ms Suu Kyi has stated many times, welcomes any endorsement of this misrepresenation by unwitting or uncaring westerners who see Yangoon as a travel destination on a par with Singapore, New Delhi or Bangkok.
Sitting around drinking coffee with upper-income Euro/N. Should you go there I would earnestly ask that you do so in full recognition of the civil liberties my friends, and all Burmese, are denied and that your testimony upon your return accommodates and if possible, advertises this sad fact.
Better still, it might be an idea not to go at all.
Nevertheless clubs are packed on weekends, everyone is drunk and cheerful. One more disadvantage of the local beautiful half of the population is that in Burma girls become independent too late.
Night life in Yangon, for a foreigner, is quite dry and boring.
I visited Yangon 2 years ago for one week and sorry to disappoint you, the only nightlife that's available (I stand to be corrected! One of the most lively places is the basement disco of Hotel Equatorial where you could find many local girls- sad to say, many of these girls are waiting to be picked up for a fee and I think you will have comunication problems with them as many cannot speak English.
As regards to not making a trip to Myanmar to protest Suu Kyi's detention, I personally fels that this will add further hardship to the Burmese people who are already suffering from the brutal regime and the worldwide slowdown in tourists.
Even though not officially allowed to open beyond midnight, you can still find bustling night bazaar and roadside food stalls in China town.
You can have nice and delicious Chinese food at a cheap price there and observe the local way of life in Chian town. Ask taxi driver to bring you to Latha Road, get off there and walk in the streets full of stalls and people.
Most bigger Hotels in Yangon and elsewhere offer some kind of nightlife entertainment.