The ride up to the top of the arch in those little conveyor cars can be very HOT this time of year; and ... a bit claustrophobic!
The view also will not be as clear on a summer haze day...
Nonetheless, if now's when you're there, it's worth it to go up once.
Stupid, though, how they have a TSA style dis-arming to make sure you don't take control of the arch with a finger nail clipper and fly it into an occupied building (/sarcasm)
The brewery tour is awesome, lots of beer tasting. The restaurant in their has some really great food too.