Local ex-pats and people who like drinking internationally are those who usually go to Canudos. It might seems as an embassy of Berlin-Kreuzberg in Tbilisi: small, with worn out wooden furniture, heavily influenced by cultural mixture like Mayan culture and Buddhism... open, cheap and cool.
If you are alone in Tbilisi, and you feel like staying out and meet some open-minded people - just go to Canudos. You'll get all-in: a drink, a talk, a good time. Staff is very relaxed and friendly, everyone speaks English; beer and chacha are cheap, and you can also get nice small snacks to it.
It's very close to Radisson: you walk direction metro Rustaveli and two pub streets (Kiacheli/Akhvlediani), and go downstairs to a small garden.
Su-Sa: 15:00-03:00