The Art Spiegelman show at the VAG was very much worth seeing. It's been bunches of places already I think, but it was worthwhile especially for illustrations of the planning that goes into Spiegelman's stuff, which seems to be driven by fear of being revealed as worthless. Made me feel healthy!
I was an early buyer of Arcade and I figured I'd seen most of the stuff, but the draft pages of Maus (and the composition of the completed pages) were great to see. It made me want to pick up MetaMaus some time.
A negative is the amount of standing and concentrating you have to do to get the most out of the show: reading comics isn't that much of an ordeal. And the later things seem to lack the smudgy charm of the earlier ones.