Mudd season is April,May, and little into June depending on location. And the mountains can get heavy snow in April. It just depends. It is the Spring season when the snow is melting and running down hill. And it depends on altitude. The lower levels and the foothills dry out sooner than the higher levels.

May is a really good time to visit Denver...as long as you don't want to go hiking in the mountains. Daytime temps are in the 70's but it'll be chilly in the evenings and early mornings. May is definitely mud season in the high country, so the hiking will most likely to be poor. I'm going to commit heresy and suggest that, at that time, you might want to skip RMNP.

If you have any interest in snowshoeing, there's likely to be some snow at Brainard Lake Recreation Area. The road is plowed partway up, so people park along the edge of the tree lined roadway and snowshoe or XC ski up to the lake. It sits at about 10,000 feet, so you WILL notice the altitude. The scenery is spectacular. You can rent snowshoes from several places, like the big REI in Denver that's right off the highway. You'd then go through Boulder, where there are no doubt, several shops that rent winter sports equipment as well. Round trip with snowshoeing would be most of a day. IIRC, it's about 1.5 hours from Denver up to the ad hoc winter time parking area.

If you want to overnight somewhere in the mountains, you could drive up to Steamboat Springs, about 4 hrs from Denver. It's a great drive and Steamboat is a really nice town.

Roxborough State Park in the SW corner of the metro area is low enough that you should be able to hike without getting mud up to your ankles. It's pretty small as state parks go, but it's got some cool red sandstone formations.

The Rocky Mountain Arsenal National Wildlife Refuge is between downtown Denver and the airport. It's often a good place to see bison, but there's never any guarantee that they'll be near a fence line. Bison do whatever the heck they want.

Someone else suggested the Wild Animal Sanctuary which is about an hour from Denver. Take your binoculars for better viewing. The enclosures are large. It's a cool place and the bears should be pretty frisky by then, having recently come out of hibernation. They have a well trained corps of volunteers on hand to answer all your questions and tell you about the individual animals.

Denver's a really good restaurant town nowadays and I think you can get just about anything you'd want.
Did you want to stay in a hotel downtown?

I'll second the suggestion to the Denver Art Museum. They have a very good collection of western art.

I don't know when you'll be arriving, but First Fridays in the Santa Fe arts district is a lot of fun. It's on Santa Fe Dr. between 8th and about 12th Ave. Galleries stay open late, food trucks complement a few restaurants along the route, great people watching, impromptu street music, and still family friendly.

I suggested a tour of Stranahan's Whiskey Distillery, to another person visiting Denver. www.stranahans.com It's 10 min south of downtown, has good parking and a tasty brewpub next door.

If you have 9 or 10 days, yes take the full day drive down to Mesa Verde National Park and stay a couple of days. It's a really interesting place.

Whatever you do, I hope you enjoy your stay here.

Does this itinerary make sense for the middle of May? (Trail Ridge Road won't be open yet).
Day 1 - arrive, pick up rental car, walk around Denver
Day 2 - Drive up the Peak to Peak Scenic Byway (1 1/2 hours) to Estes Park. Spend the day adjusting to the altitude in Estes Park. (Small shops, etc.)
Overnight - Estes Park
Day 3 - Rocky Mountain State Park - hike Bear Lake Trail to Emerald Lake (approx 3 hours)
Estes Park JazzFest
Drive to Boulder
Overnight - Boulder
Day 4 - Boulder - Possibly tour Celestial Seasonings (tea)
Eldorado Canyon State Park - Hike the Eldorado Canyon Trail (3.5 miles one way) for canyon views
Overnight - Denver
Day 5 - Hot Air Balloon ride
Red Rocks Park
Days 6 and 7- Either Denver (U.S. Mint? Molly Brown House Museum?) or Colorado Springs (Garden of the Gods, Pike's Peak)

Where do you overnight on Day 1? Where will you walk around Denver? I suggest Cherry Creek North for shops and cafes, or Washington Park for walking.

Be sure to have a Plan B, in case of rain.

Day 4, you could overnight in Boulder so you don't have to change hotels. Just drive to Red Rocks from Boulder.

I've not heard of hot air balloons at Red Rocks. It would be fun, if you like that sort of thing.

For your final nights, I recommend Denver. Or even Golden, rather than driving down to the Springs and back to Denver airport.

I like the Bear Lake Trail to Emerald Lake but check trail conditions, bring proper footwear and possibly poles.

http://www.nps.gov/romo/planyourvisi...conditions.htm

http://www.nps.gov/romo/planyourvisi...conditions.htm

There is still a lot of snow up there, but temps are warming up so there will be melting slushy snow, icy spots, and mud.

I think you are going to need more than a plan B. You still haven't told us when you are coming other than mid May which is the middle of this week. What are your exact dates?

Just to give a weather update. Today, we are in the middle of an extensive snow storm. Maybe a foot in the city and considerably more in the mountains. While the snow in the city will be gone in a day or two, the snow will still be in the lower foothills which could make many of your planned hikes messy. There are reason why we call May mud season.

If you go to the Celestial Seasonings tour (which is in the suburb of Gunbarrel, a few miles east of Boulder proper, a 15-20 minute drive), make time for a stop at the "Leanin'Tree Museum of Western Art" (www.leanintreemuseum.com); it's 2 blocks away from Celestial, free, and has a really nice outdoor sculpture garden and easily viewed small gallery inside.