Things to Do in Utah and Colorado

Colorado hands down. Others have given all the things I would have. It absolutely stunning there. Enjoy.

I am going to respond on the case of Colorado having more to see, more things to do, and an all around better place to visit. (Yes, I have vacationed in Utah and aside from Moab and Arch's I see little that can compare to Colorado.)
Colorado has so many things it depends on what you are interested in. There are many microbrews in Colorado and SO many tourist sites. Thinking of some sites in Colorado; Royal Gorge Bride (Canon City) is the worlds longest suspension bridge and is quite gorgeous, Garden of the gods (gorgeous), Cave of the Winds (just cool), Pikes Peak + trolley etc., Air Force Academy (Impressive) ... Denver has the Art Museum, the wildlife Experience, Coors Brewery, etc.
Colorado has so many things to see. if you are interested in outdoors you can take U.S. 50 from Canon City (Royal Gorge) and head up into the mountains to see and go on wonderful adventures.

Telluride and Vail are both really cool towns to bum around!

Park City, UT all the way! Main Street is awesome. You can stay right there.

Check it out online.

You should rent a car to get to everything you'll want to do including water sports and hiking and zip lining, etc.

I have spent tons of time in both Colorado and Utah...if you're planning on flying to your meeting place, might I suggest Jackson Hole, Wyoming. Absolutely stunning area and lots to do, State parks, hiking, hot-air balloons, wild-life, soooo much fun! It can be kind of spendy in some aspects, but if you plan ahead and have an itinerary, a ton of fun can be had without spending a fortune. Enjoy your vacation!

We just came back from colorado springs!! Lovely, and beautiful.
You will probably have to rent a car.
Or call and see if there are bus tours.
We stayed there for a week and I wish I had more time.

I'm pretty sure you'll at least have to rent a car. The Denver airport is about 30-45 min. from downtown Denver. I go out there a lot, and while it's a beautiful place to visit, everything's really spaced out, a car is a necessity. I would head north to maybe Boulder or Estes Park so you're in the mountains.
If you want a city where you can get off the plane, walk to a nice hotel near great restaurants, shopping, movie theaters, museums, historical walks...go to Boston! There's so much to do there and it's easier to not have a car and just walk or take the T (subway).

I live in Utah. I would recommend Park City (you'll need a car from the airport though) or the Jackson Hole Wyoming suggestions.

Park City has nice restaurants and shops, spas, skiing in winter, hiking. There is an Alpine Slide where you ride a rolling sled down the mountain. There are a lot of fun outdoor activities.

You could also stay in downtown Salt Lake and still hike nearby, but the Salt Lake Valley is really suburban and spread out. It is not really a walking kind of place.

My girlfriends and I always choose Jackson, though. It is beautiful and a very laid back atmosphere. Tons of great restaurants and shops. It is easy to walk everywhere.

I thought Pearl Street in Boulder, Colorado was very cute and lively... lots of restaurants and a darling neighborhood... Also nearby and if you like a burger and want to keep it simple but good.. Larkburger was tasty.. again, simple, inexpensive and good.. at least a couple of years ago it was..
Also....
In utah, off the beaten path and just fun to check out is the Gilgal garden, you can google it.. small, fun and quirky sculptures.. If you like that kind of thing, which I do.. then you ll like that.. at the time, it was free..
went to the red iguana.. was not impressed.. people many mention it, but I thought it was overrated..

Colorado Springs would be an awesome experience for both of you. You can stay in many areas nearby, even Denver, and still go to Pikes Peak or visit many small towns with various shops and fun things. I love this area.

East of Denver I swear if you look hard enough you can see New York. There is NOTHING to do east of Denver. West of the mountains there isn't much to do there either.

Coming from Flower Mound you can go up through New Mexico and stop at Taos and maybe even the 4 Corners area. Those are really nice places to visit too. I would take at least a day extra to go to all those museums in Taos. I love walking through and looking at Georgia O'Keeffe art. It's inspiring and I can understand it.

If you go to the Provo/Salt Lake City there are lakes where you can rent water rides and there are so many activities one can do there. There is a huge mall that we visit every time we go to the area. My hubby's grandfather was a baker at the ZCMI bakery for years. I loved going to a cart and buying caramel clusters. I could live in that mall. We loved to go eat at Lion House restaurant too.

If you have any interest in genealogy you could do a side trip to the family history center. I found my great grandmother's brother's enrollment papers to the Civil War. It was so darn cool! They have tons of people to help too.

There is also the zoo, museums, hiking areas, and many religious sights to see. I would pick Utah hands down. There are only a few minutes of driving if you want to go from one city to another. It's one big megalopolis now.

You can send off to get official travel books that are broken up into sections. If you are really big outdoor people you could even go to the more southern part of the state. The Arches park is phenomenal. Talk about hiking where old western movies were make and you can just feel the history under your feet.

You can go white water rafting in the park too. It's just awe inspiring.

Utah Utah Utah

Colorado isn't too shabby either but it's one flat prairie then mountains then more flat space until you get to Utah.