I disagree with some of what has been recommended for a first-timer with your constraints. I would suggest that you stay in 'downtown' Frisco, a wonderful, little town in Summit County, centrally located right among all of the ski resorts. Frisco has been a town for over 150 years, has lots of great dining, shopping, and even a historical museum, and is the preference of many of us 'locals'. Your friends can walk around Frisco, and you or they can take a free bus around Summit County, as works best for your plans. That bus gives you access to Breckenridge, Copper Mountain, Keystone, and Arapahoe Basin. Yes, discount multi-day lift tickets are available that can be used at Keystone/Breckenridge/Arapahoe Basin as you wish. If you drive to Vail, your friends won't be trapped, as they can get to Breckenridge or wherever via bus. Frisco tends to be considerably less expensive than staying at any of the resorts, and (not to advertise) I can rent you a truly fantastic condo on the river in Frisco the first week of March if you'd like to contact me.