August 2013 trip with the girlfriend.

Utah residents here. We are planning on moving out there in 2015 and will be taking a trip there this coming August. I looked at top 25 attractions but would like some local input. We love science. She is fascinated with genetics and chemistry, I love astronomy and physics. We both love Italian food, I love salmon. I'm a trail runner, she likes pretty hikes that are 5> miles. She's turning 21 that week and we drink a little... I support marijuana.

Given this information, what would you say will be the funnest, neatest things to squeeze into 4 days?