Basically, everyone is going to be eating and drinking in the Byward Market area, as it’s the highest concentration of bars and restaurants close to the convention center and to major tourist attractions like Parliament. I’ve suggested a few places in that area, but also some places a bit further afield for folks who like to walk or who are willing to bike/drive/take a taxi. The other “main drags” in downtown Ottawa are Elgin St. and Bank St.
Bottom line: the best places to drink in Ottawa are The Manx (walkable from the convention center; hidden in a basement; great cozy, buzzy atmosphere; excellent, changing food menu; really popular) and Pub Italia (not walkable; has the only world-class beer selection in Ottawa; big draft list plus hundreds of bottles including lots of rarities and obscure Belgians; an essential stop for beer geeks like me).
See also this list of local pubs produced by the meeting organizers.