If you have time, get up to Lyons Classic Pinball (open Thursday - Sunday afternoons/evenings). Lyons is about 15 miles north of Boulder and they have 30+ games in excellent condition, including a beautiful AC/DC BIBLE. They have everything from classic EM's to modern Sterns.
Closer to Denver, Lakewood Grill is a good choice. Last time I was there they had Starship Troopers, Iron Man, Avengers Hulk, Twilight Zone, Dracula, and Skateball.
Downtown Denver has the 1up. This venue can be very noisy, but the 15 pins there are top notch. Also, 2up isn't far away and has good titles, though I haven't been there yet.