In reply to Sl@te Head:
Hi Ian
I'be been fortunate enough to have about half a dozen 3-week trips to Colorado in recent years, usually in September as summer is too hot for my comfort.
I don't have much knowledge of accommodation, as I have a friend with a house in Breckenridge in the Rockies - this isn't a climbing area but is a reasonably good base to travel from. When we need to travel further afield we just use a motel for a few nights. Boulder is the hardest area to find somewhere to stay cheaply. That said, last year a couple of friends booked an apartment in Eldorado Springs - they arrived just in time for the floods!
I'm guessing you will be looking for a family holiday and not looking for too many soul-searching experiences, otherwise I'd say that it's the longer trad routes in Colorado that are by far the most memorable - places like Lumpy Ridge, Eldorado Canyon, Turkey Rocks, etc. But there is enough sport climbing to make a trip well worth while. You will need to find somewhere high up or in the shade in summer.
For a good selection of routes right across the state I recommend the Stewart Green guide Rock Climbing Colorado. Additional info from specific area guidebooks and the Mountain Project website.
Boulder Canyon - mix of sport and trad, shade & sun Sport Park is pretty scruffy but Tonnere Tower has longer bolted routes (but not in the Stewart Green guide). The grades of newer sport routes are fine at the usual UK/US grade conversions, but my experience is that old style 5.9+ is more like E2 than HVS.
Shelf Road, near Canon City - good reputation for sport climbing but I've never visited it.
Clear Creek Canyon, near Golden - lots of crags, sun and shade, nearly all sport. Low down so hot in summer. Near busy road but occasionally some "interesting" approaches. One good additional crag not in the current guides is Canal Zone (see Mountain Project), but beware of rattlers!
Red Rock Canyon, near Colorado Springs. Not great but worth while for a change of rock - bolted sandstone slabs.
South Platte - this is a huge area of granite walls and domes that most Brits have never heard of. Woodland Park might be a good base for this area. I would particularly recommend Eleven Mile Canyon near Lake George - there are several crags in this valley near the road and with stunning scenery. Mix of sport and trad. Beware the grades, especially on slab routes - 5.8/5.9 can sometimes feel like UK 5c.
Rifle - far too hard for me! Boring overhaging limestone.
Independence Pass, Monitor Rock, not far from Aspen - high up, so a place to escape from the heat, though the altitude of 10,000' makes climbing seem like hard work. Lots of bolted routes at 5.8-5.10.
Vedauwoo - actually in Wyoming but not far away. Again, stunning scenery and humiliating grades. Infamous for cracks and offwidths but there asre enough bolted routes to make a visit worthwhile.
Hope these comments give you some ideas.
Post edited at 10:49