The Marriott Steamside is a time share operation. It is about 2 miles west of Lionshead on the South Frontage Rd. It does provide pretty regular shuttle service to both Lionshead and Vail Village.
The A,B,C,D (Aspen, Birch, Cedar, and Douglas) buildings are a bit older, but still fairly nice. At least better than a basic hotel room. The E (Evergreen) building is much newer, and has some really beautiful places. There are indoor pools, saunas, hot tubs, etc, but no restaurant on premise. Shopping at the Safeway or City Market (both super markets) is less than a 5 minute drive, just on the other side of the freeway. I believe the shuttle will also serve that. Most of the chain/fast food places are within a 5 minute drive to, as well as a very good Sushi place and a good Chinese restaurant.
As dp mentioned, the Marriott Mountain Resort is just a few hundred yards from the base of the Gondola and CH 8 in Lionshead. Recently renovated, it has really been done nicely, but the price tag will give you heart failure (better make sure you are there the same time as dp's meetings...
The only children's ski schools are at Lionshead and Golden Peak (the far side of town from either Marriott). Rental shops, restaurants, and other shopping are spread out all over Lionshead and Vail Village. The intown bus service is free, and pretty good. It'll pass by about every 6 minutes or so.
I hope this info has been of help! If you have any further questions, either add to this thread, or PM me.