Townies from Stoneham might tell you Allston/Brighton and Cambridge are the coolest spots around Boston, but the former’s too fratty, and the latter too pretentious. Somerville is the "just right" porridge, even though it's not Boston proper. While the area's blowing up, thanks to a HUGE infusion of cool bars/restaurants and the impending Green Line T expansion, the once-dubbed "Slummerville" still maintains its artsy, small-town feel.
And much like Huey Lewis suggests, it's hip to be square in Somerville. Or, at least in one, anyway. Newer spots like Bronwyn, Somerville Grooves, and Union Square Donuts have brought plenty to Union Square; at least eight new restaurant openings in the last year have made a scene in Assembly Square; and new venues, like the retooled Rosebud, or Saloon, a pre-prohibition era whiskey bar, have sprouted up in Davis.
And if you're not into bars and restaurants... well, you need to change that. But Somerville does host two fun music festivals, PorchFest and HONK!, so there's something for everyone.