Well, obviously the best place to enjoy a pint is anywhere you bring your homebrew and some friends! :-D
But if you're in between batches, hopefully you've already hit the bigger breweries. Even if they're a bit crowded at times, they're still fun places with good beer:
Deschutes Public House - I just really like their beers, this spot is a decent restaurant too.
Rock Bottom Brewery - Good beer sampler. I was just there a few weeks ago and loved their seasonal wheat beer, but I can't remember what it was called.
McMenamin's Kennedy School - See a movie. On a couch. They'll bring you beer and pizza.
Hopworks Urban Brewery (HUB) - Organic beers, I really dig their IPA when I can't find Ninkasi's Tricerahops.
Roots Brewery - Another organic brewery, just across the river in SE Portland, off Hawthorne, I think. Try a Heather-tip beer brewed REALLY old-skool style, before they had hops.
Lucky Labrador - Over in NW off Quimby and 20th, very cool, very relaxed place. Either they're never busy, or people don't know it's there! Good beers, big place, "undiscovered".
There's a bajillion places in Portland, these are just the ones I've been to recently that were a great time with good beer.
Cheers!
-Troy