Skip the Museum of Discovery if it's just you and Karie. The local blood center, Garth Englund, where I do my platelet donations threw an appreciation dinner last fall there. It was interesting but I'd think would be far more enjoyable with kids old enough to appreciate history and science, say 6 to maybe 12. Two adults on an anniversary trip - nope.
For culture, check out the Lincoln Center to see if anything's going when you're here. It'll probably be La Bete, which is playing now.
The Aggie Theater is downtown FoCo and that's where the big names would play. But rarely would there be anything there you don't already get touring through Denver. As mentioned, Avogadro's would be a better choice for a random drop-in night. Plus they have food, tables and you can hear acoustic & folk and still make a night cap downtown.
Another place I think is neat is the Center for Fine Art Photography. Not sure if there's an exhibition currently but if so that's worth a stop.
Do try to see a movie at the Holiday Twin (the drive-in) some time, but last weekend was the last of the season unfortunately.
You can do the standard brewery tour and that's all well and good but if you want to just check out some local places there's so many more than just those now. I'll admit without reservation that hanging out at New Belgium's outside beer garden is fun on a nice day...
Regulars on our rotation are Zwei (Harmony and College), Prost and Coopersmith (Old Town) as well as Grim Brothers, Big Thompson, Big Beaver (all in Loveland). Only Coopersmith's has a full menu restaurant, but most usually have a food truck.
I also like The Whiskey downtown in Fort Collins, which is as the name implies a whisk(e)y bar. They have a decent menu, too.
I'm not sure there's really anything up here that is a don't miss compared to Denver as far as food. We like Canino's on College south of downtown for italian. It's not as hip (which is good IMHO) and I thought the food is at least typical of the average you'd find on The Hill back in St. Louis. It's not Zia's, Gitto's or Gian-Tony’s, but it's pretty good.
We like The Next Door (Door 222 now, thanks to the stupid place in Boulder suing them over naming rights) here in Loveland. Their menu is very fresh and very local. The woman who runs our CSA, Amy, sells her excess produce to them and that's pretty typical of the source for their ingredients, hyper local farms. Same goes for our butcher, The Bull and Boar, who gets his beef and pork from a single rancher in north Fort Collins. They don't have a restaurant per say, but a deli counter. The beef brisket sandwich is $5 super well spent.
Tasting at Odell Brewing 
