hey, it really matters what you are into. If you open to different places, you shouldn't have a very hard time finding anything. the usual expat bars include sugar, gibraltar, el alamo, puerta roja, casa bar, shamrock and kilkennys. out of those, puerta roja is probably my favorite, but that's just me. also good choices are acabar, jobs, mitos argentinos, milion and tabacco. as for clubs (boliches), museum and club araoz are pretty good.
Let me know if you need any more help...
Cheers!