There's certainly an appeal to specific formats like 70mm, but that comes along fairly rarely. I haven't been to Portland, but I have seen 70mm films in classic theaters. They're rarely comfortable, the sound usually sucks, and the lack of stadium seating can be brutal, but you're there for the insane effort that went into end-to-end 70mm production.

Of course, I saw Dunkirk in IMAX 70mm projection at the Metreon in San Francisco, which is a state of the art screening room, but that will probably only ever happen every few years. Sadly the Metreon recently remodeled with completely terrible seats (only in the IMAX room), so I'm rarely tempted to go there.