I would highly recommend cbar. Machines are generally better maintained than GK. Good beer list, good food. Ship Ahoy is a dive bar across the street and there are 4 more pins there. GK is still a great spot though, just based on the number of machines they have. POP is great, they have a nice mix of machines. Say hi to @heyrocker while you’re there. Other must hit locations are probably Blackbird (about 10 machines and within walking distance to Hawthorne Hideaway which has 5 more pins), and Scoreboard. There are also tons of other great locations with 3-5 machines.
Pinball map is your friend. I would meet up but unfortunately I’ll be out of town. Join the pdx pinball Facebook page and make a post when you get into town. I’m sure someone will be down to play some games.