AMWS
I attended both phases of the basic course in 2005. It aint Ranger school, but it isnt a walk in the park either. Most days start with a 1-2 mile ruck to the training sites. Not too bad distance-wise, but there is usually a 800-1000 foot elevation change in the short distance.
Winter phase focuses on basic rope-work and alot of winter survival. About 5 nights are spent out of doors, 3 of them being during the final exercise, to use the skills that were taught in a more realistic environment. Very little tactical training, but a whole butt-load of technical training. Movement techniques are also taught and reinforced, with the daily ruck movements being performed on skis and snow-shoes. There is more time spent in-doors in this phase, totaling about one training day.
Summer phase is almost entirely outside. Lots of time spent balance-climbing on top-rope. The movements are longer here, as the movement is not hindered by snow. Dont be fooled by the title "summer phase" though; it's summer in the mountains. When I was there it was only 50 at the highest (in May), and it rained a cold rain about 3 or 4 days. i heard stories from the cadre about times in the past when it snowed during summer phase.
All that being said, the month that i spent there was one of the most rewarding experiences of my Army career. The carde is second to none when it comes to mountain knowledge and experience. they are tough and very no BS. they want the students to learn and have fun doing it, so the usual level of army over-regulation present at most TRADOC schools is kept to a bare minimum. Make sure to listen and obey their instructions about safety; they will toss you out for willfully violating safety rules.
One last note. the chow there is the best food I have ever had at an military facility. The cooks are long-time National Guardsmen who have been cooking there since Christ was a corporal, so they cook the food like they would want to eat it, not how the Army says they should...
Be safe and have fun!