I've lived in Chicago (went to UChicago undergrad), but I haven't been to Portland or Vancouver. I went to LSA in 2009 in San Francisco and it was really great, but FWIW don't feel like I'm equipped to compare LSA and ACL. I was pretty new to Linguistics in 2009 so LSA was a total smorgasbord of awesome excitingness—Optimality Theory, multiple sessions on sign language stuff, a whole bunch of cool work that I'll probably never work on but really neat to know it's going on and look for connections to my own work.
Chicago is great, pretty affordable, and has full coverage in public transit (better to fly into Midway airport than to O'Hare, though). But it's spread out enough that If you go to Summer Institute you should definitely stay in Hyde Park, and not even consider looking anywhere else to commute to U of C campus. It will also be very hot in July, and though I'm not sure how the heat index compares with Gainesville in July, the housing stock in Hyde Park is old enough that you cannot count on everywhere being air conditioned: on-campus student housing will have A/C, off-campus might not.
DSNA always has both a high-end and a budget accommodation option, and actually the $56/night for a private bedroom in a four-person suite (http://events.arts.ubc.ca/dsna-20&shel-9/travel_and_lodging/index.html ) sounds like a pretty good deal for the budget end. The budget accommodation has always sold out before I've gotten around to booking it for every conference I've attended, but maybe this year I'll get to it sooner.