You could go to a Wunderland nickel arcade - there's three in Portland (go to wunderlandgames.com). They have DDR and other Konami music games (aka Bemani) such as Guitar Freaks and DanceManiaX. I went there to get my DDR on and got really good at Heavy. :3 (I competed in the DDR tourney at the con.... lool, I was the girl who got the farthest, and then there were guys left...)
Bubble Bubble Tea has two locations and they serve a wide variety of boba and good snacks :O~ They're awesomee!!
I go to Lloyd Center Tilt a lot just because my DDR friends hang out there now, there's In The Groove 2 and like, lots of fighting games, and Initial D... the three things that probably make that place worthwhile.
Century 16 theatre on 82nd and Holgate is awesome... (my favorite chain theatre in town!) they have a DDRMax2 machine (a rarity for the portland area), and it's on Joint Premium so you can play double or versus for the price of single ^__^ <3
Hawthorne has some awesome shopping. Around 42nd avenue, there's a place called Trendy City that has bubble tea and lots of cool asian things (Hello Kitty, Sanrio, Totoro, etc.) they sell :O
While there is Backspace, don't forget about Ground Kontrol right aruond the corner... retro arcade games!