With a name like the Greatest Bar (262 Friend Street, Boston, 617.367.0544), this place has a lot to live up to. That could be why the fourlevel hotspot is hosting Uptown Saturdays, where drink specials abound and the music is diverse. They’ve got DJ Uptown (we see where the name comes from) playing Top 40, mashups, and house on the first and second floors, and oldies and Motown hits on the upper levels. The doors open at 10 p.m. and it’s a mere $10 cover — a small price to pay for the greatest night out.