Yes, Trailrunner, they'll need the rain gear! The Rockies at that altitude feature sometimes daily heavy thunderstorms with rain, hail, sleet, snow, high winds. And when it's raining, it will be cold--none of these warm Pacific Northwest drizzles.

SquareGlobe, here's what I'd leave out. First, the short sleeve shirt. UV rays at 10,000-11,000 feet are really fierce. I suggest you keep well-covered rather than depend on sunscreen. You'd need a thick, clownlike layer of sunscreen frequently re-applied to do any good. A hat that shades your ears and the side and back of your neck, but doesn't interfere with your pack, is a good idea, too. You can buy or sew a drape for a baseball cap that will shade your ears and neck. Here's an example. At the other end of the spectrum, I'd also forget the down jacket. Your rain jacket over the primaloft jacket and a base layer, plus hat and gloves, will be more than warm enough. I'm personally not a fan of wool--first, it makes me itch, second, it absorbs a lot of water, and third, it gets really heavy when wet. Your Mileage May Vary; there are lots of merino wool fans on this forum! As Jim suggests, a heavier base layer would be better--something midweight (Capilene 3 or REI MTS midweight). With breathable rain gear, you don't need the wind shirt--it won't be that warm if it's windy. Again, a wind shirt is a useful item for Pacific NW drizzles, but not for the Rockies where the weather is more extreme. Your rain jacket will double as wind protection--when you have to wear it, it will be cold enough that you won't sweat inside it.

This summer I'm going first to northern Colorado and then to the Wind Rivers in August (each trip for a week), and here's what I will take for clothing, based on years of experience at high altitudes:

Wear (assumes I'm starting out in fair weather):
Shirt, nylon, long sleeve, ventilated
Pants, nylon, long
Undies, breathable nylon (Ex-Officio)
Socks (Thorlo outer and polypro liners)
Boots (I'm a boot person due to ankle issues, but I get them as lightweight as I can find)
Sunday Afternoons Adventure hat--I just got this and it's exactly what I've always looked for in a sun hat for backpacking! It makes me look like a mushroom, but who cares.
Cheap cotton gloves with fingertips cut off for sun protection; they go into pack at the first hint of rain.

In pack:
Base layer, Patagonia Capilene 3 (for sleeping as well as base layer)
Socks, 1 set (I rinse out the liner socks every evening; they dry very rapidly even if it's wet)
Underpants, 1 (I can do the same as socks, but I usually just change half way through the trip)
Jacket, Montbell Thermawrap UL (lightweight synthetic insulated jacket)
Balaclava, polypro fleece
Gloves, polypro liners (absorb very little water, dry fast)
Rain mitts (Mountain Laurel Designs)--worn over gloves to keep hands dry and/or keep out cold wind. You could use plastic bags.
Rain jacket
Rain pants
Low gaiters (I may not take mine, but if you use shoes instead of boots they are great to keep rocks, etc. out of your shoes)
Mosquito head net (I hate putting repellent on my face)
Mesh shoes with rubber soles (SprintAquatics) for wading. Occasional camp shoe use, but I usually just loosen my boot laces.
Bandana--with my kitchen gear--its primary function is as a potholder.

If I didn't already have the Montbell jacket, I'd take a 200-weight fleece jacket. The Montbell is almost too warm. I won't wear it over a base layer unless it's actually freezing.

I never do laundry on the trail except for rinsing out socks and (if needed) undies. I don't like to use soap in the wilderness (pollution), and all that wringing is a lot of work. Spot-cleaning is normally the most that's required (it is important to remove food spills!). I will, however, visit a laundromat between the two one-week trips, and of course I'll have a complete change of non-hiking clothes hidden in my car!

Which reminds me, any non-hiking items that stay in your car while parked at the trailhead should be well-hidden (do this long before you get to the trailhead). Leave nothing of value in the car. Unfortunate fact of life everywhere.