It really depends on what you like, both in the saddle, after the ride, and on days when you want to give your legs a break. Also, the time of year makes a big difference. Summer in Moab/Fruita? No way, unless you can watch the weather and go when the forecast calls for mild temps. Fruita will tend to be cooler and you have the option of higher elevation riding, like Palisade Rim, which is close by. Spring in CB? Mudfest, forget it, especially this year since they got a lot of snow. CB in July? Heaven, if you can ignore the crowds. Nice ambience in and around town? CB is the place, always.
I’d do Moab and Crested Butte. Maybe hit a day of Fruita when you drive between the two. Fruita and Moab will be hot, Crested Butte will not. Go to Crested Butte last as every day matters that season. Rode the 401 on the 4th of July and there was one crazy snowfield and then the last part of the climb was rough (the return trail part was dialed!)
For that time of year, I would hit Crusty Butt and spend the week there! Couple of things to consider besides temps: Depending on where you are from, you will likely need a couple of days for your body to begin to acclimatize to the altitude (town around 9K feet, everything pretty much goes up from there…) and there are enough trails in that area to go and ride for a week with little repeat or doubling the trail. Fruita, in my experience is a little short of riding for a full week – and Moab, while loaded with rides, is a lot like Fruita, HOT and rocky. I love Moab, but the temps in the summer might be harsh for longer rides that you can’t finish before early afternoon. If it were my trip, I’d hit CB for the July dates, but if I was going earlier or later in the season, a few days in Moab and a few in Fruita and get my rock on. That’s my opinion after multiple trips over the years to all the locations – your desires and preferences/heat-soak ability, etc… might make you go a different route. Some friends are heading to Moab in late June, and just start early in the day and try to finish before 1:00, and hang and the hotel pool drinking the rest of the day. That can work too. Regardless, have a blast!
I second bonkedagain here. I LOVE both Moab and Fruita, but July in those places is intolerable. If you MUST do two of those three Moab and the Butte are the answer. But beware: you’ll want to get out early in Moab to beat the heat. Good news is by July, The Whole Enchilada will be open.
Like Greg, as a destination, of the three, I would skip Fruita. However, Mark is wise to point out that you can easily hit Fruita for a day ride when in transit from one to the other. Since you’re going that way anyway, it’d be a shame to miss it entirely.
Perhaps Salida and CB. You can spend days between them. Hit the Monarch Crest or Canyon Creek Loop on the west side of the Divide. Salida has enough to keep you busy and not as hot as Fruita or Moab. If you want to go further perhaps Durango.