Well, it depends on how involved you want to get at the two museums. If you take pictures of everything and read up on each display, it would take hours. I took some pics of the glass and strolled thru pretty quick, same for the pop museum.
I bought the City Pass too, so got there right when the glass museum opened and picked up my booklet. No line, so it was quick. Saw the museum and then the Needle has timed entries so had to wander a bit to kill time and then got in line for that. Then went to the pop museum. If you are pressed for time Iโd say you could do an hour or so at each museum and even less at the Needle, although you do have to wait in line for that one. I canโt remember, maybe they let people up every half hour or 45 min.?
I wanted to go back to the Needle at night for my 2nd visit, but never made it because I was down at the waterfront.
I visited mid May too, 2019. Crowds werenโt too bad. Itโs cool that three places were right there together to use the City Pass on.