How would you spend a month in Colorado?

If you're not looking for a thru-hike I'd plan an extended trip in the San Jauns than hit a few other areas. One idea might be to try and put together a loop through the San Juans using the CDT and CT and a few other trails. You could get about 80 miles or so of wilderness travel through the Wimenuche for example. After that if you have a vehicle you could take a few days off than do shorter trips through other areas. Lost Creek is unique, the Sand Dunes are a bit different and the Sangri De Cristos are a nice mountain range. The Front Range (RMNP etc.) is very scenic but not nearly as remote so its better suited to shorter trips or day hikes.
I'm curous though why just Colorado? If I had a month I might want to see some of Wyomoing too.

you can get better (marginally) views than the CT by doing that same stretch and using the routing of the CDT. THEN you can say that you are doing a section hike of the CDT, which i opine rates better hanger talk than the CT.

a bit further south i am particularly fond the CDT section below pagosa springs.

it's hard to muck up a whole month in colorado. you really can't go all that wrong.

I simply like Colorado. Grew up camping there, but have only been back a couple of times in my adult life. As for Wyoming, I had a chance to spend some time in Wyoming three summers ago. Teton Crest trail with two twelve-year-olds. Great times.

Am I hearing a push towards the southern end of Colorado? I've been in the Durango/Silverton/Ourey area via car…and I have to agree that the area is stunning.

I probably won't rent a car for the entire month. I have a couple of friends in the area (who will also probably spend some time on the trail with me; not hikers, though I hope to convert them)…and then there is public transit after that.

Scenery wise southern Colorado is hard to beat. My main reason for suggesting that area is the size of the wilderness areas. I think RMNP, Ten Mile Range, Indian Peaks, etc. are all awesome they just aren't as big or as secluded.
If you want to use public transportation the San Juans aren't that easy to get into from Durango you can fly to an airport near Durango and get a shuttle to the city. From there its just a couple miles to the Colorado Trail's south end so you could head into the San Juans from there. Its pricey ($85 I think) but you could hop on the Silverton Durango Railroad to get from Silverton back to Durango. With those options you could try to do some kind of big loop that would keep you busy for a while. If you make it all the way up to Brekenridge there are buses from there to Denver. I don't know where you could get rides form your friends.
I would look up PMags guide to the Colorado Trail, he lists all the public transportation options and resupply options along the trail.

+1 on southern Colorado. Spent a little time in Weminuche last summer and just loved it.

If I was in SW Colorado, I'd have to slip over to Moab for a few days and do some canyons.

Well, I grew up in Durango and Silverton. I love those towns and I especially love all the mountains around there. So please spend some significant time up in the high country there.

But living in the Fort Collins area for the last 10 years–I have discovered that this is a great town. So please think about spending some time at the New Belgium and Odell's Breweries. Great beer!

You have excellent taste, Joe. The problem with combining those two areas is that the appropriate seasons don't work out well. The Moab/Canyonlands area gets too hot after early to mid-May, and the snow hasn't melted by then in the San Juans. Maybe a September trip could work, but that might still be too hot in the canyons for my liking.

I think I'd drive around the state doing three or four 5-7 day backpacks, each in a different location. The San Juans–new territory for me. Second, the Gore Range. The third, Mt. Zirkel Wilderness near Steamboat Springs. The second and third would be to revisit places from my childhood and teenage years. I'm not sure where I'd go for the fourth, but, like the first, it would be to a place I haven't been before.

This might give you some ideas:

http://www.coloradowilderness.com/wildpages/map.html

Colorado has more acreage as designated wilderness than any other state except Alaska. Research the wildernesses before hiking them, though. Many (like Hunter-Fryingpan) generally only have large collections of out-and-back hikes without many thru-hike or loop opportunities.

I have GOT to +1 the San Juan and Weminuche wildernesses. That's an area on my wish list- specifically the CDT section through there. Honestly, I think that if I were in your situation that's probably what I would do. I worked out a 2-week route once that included some hot springs, but never got to try it.

Other thoughts:

At 10-12 miles/day you couldn't complete the CT in 30 days, though you might be able to at 16-17 miles/day. I have only done a couple of sections, but I'm convinced it's a great option nonetheless. I DREAM of thru-hiking it some day.

As others mentioned Great Sand Dunes is an incredibly interesting area in a way that is entirely different from any other national park- I have a trip report on it here on BPL. I'm actually very fond of it, and being just a couple of hours from my house doesn't hurt. But you could never spend 30 days there- it's pretty small, unless you add on a comprehensive trek through the Sangre de Cristos as well. Nonetheless if you wanted to hit several different areas instead of one big 30-day hike it would be a diverting contrast.

Lost Creek Wilderness also has the virtue of being close to my house and is indeed it's own unique thing, but nestled as it is nearly mid-way between Denver and Colorado Springs it can get "crowded." Not ridiculous mike most national parks, but if you're looking for true solitude and remoteness it isn't what you're looking for. If you want solitude stay farther west. But there are opportunities at Lost Creek to connect several loops into a large uber-hike.

Another thing to consider if you're breaking your 30-days into smaller chunks would be the Maroon Bells 4-pass hike. It is so beautiful that it looks Photoshopped. And there are numerous loops through other areas of the wilderness that you could connect together to make a larger more epic trek if you wanted to spend more time there. The only problem is its popularity- lots of other folks on the trails, particularly near Aspen. And if you want to start or stop at Aspen finding places to leave your car can be problematic. But on the plus side the bus takes you straight to the trailhead! It's actually easy (if rather expensive) to fly into Aspen and bus to the start point. But, Dear God it is beautiful!

Another spot on my wish list is Flat Tops Wilderness- you could spend forever in that place, just like the Weminuche. I worked out a route there too, once, but again the hike fell through. It is not the classic high-alpine hike people think of when they think of Colorado, though.

Wow, I can go on and on.

What month are you doing this? That might narrow things down.

Within close proximity to a brew pub.

Eugene – word.
Whatever happened to the good old fashioned dayhike followed by microbrew beer.

Honestly, you don't always have to run an ultramarathon, sometimes a 5K is good and you can enjoy your dinner!

Thanks y'all. I sure appreciate all the input.

Keep it coming if you got some more.

I would acclimatize for a week just before labor day then run the Silverton 1000 Mile Challenge.

http://www.silvertonspecialevents.com/silverton_special_events_033.htm

I would combine wilderness backpacking with Euro style backpacking in S.W. Colorado. Drop down from the backcountry into towns like Ouray, Silverton and Lake City to hit up hostels, hot springs, maybe even ride the train and get the best of both.