Is a day trip worth it?

Depends on your enthusiasm, energy level, and sanity. I've been to a decent number of places, and the only nights I've spent were in GPT w/my brother, in MCO w/my best friend, and in LGA(in LGA, in the most uncomfortable chair) by myself. I've taken plenty of day trips.

I'd say go for it, the weather in ORD can't be much better, and probably is worse, than the weather in MDT, and I can't wait to go south. If you can warm up even for a day, do it.

I've never done a day trip to CVG or ATL, every trip I've taken requires a connection. 5 hours down, 5 hours on the ground, 5 hours back. A 3 hour nonstop really isn't that bad.

You could definitely get to MIA and back in a day, just depends how much energy you have.

My next trip planned is 2/18 to DEN to see my beloved Colorado Avalanche take on rival Detroit Red Wings. Technically a day trip? Not sure, hopefully leaving 6:30am, arriving 11am, taking red-eye back at 00:55am and back in MDT at 11:30am. Not out and back in same day, but no hotel either.

Have fun with whatever you decide to do.