If you're planning a week long trip here's what I recommend.....
Stay in Whistler Village (or surrounding area) for a couple nights and ride the mountain for at least 3 days. If you buy a Whistler Edge card (1, 3, 5, and 10 day passes) prior to heading up there, you'll get a discount on the lift ticket prices. The Edge card will also get you discounts at places all over the village, including lodging. Once you sign up, you can sign up for monthly emails that include different lodging deals (which is a pretty good way to go). As for specific hotels, I usually get a condo with a group of people when I go up so I don't have much experience with the hotels in the village. I have stayed at the Adara (Whistler hotels - Boutique Hotel | Adara Hotel
) a couple times and gotten decent rates (~$100/night). Staying in Squamish would be cheaper, but if you're gonna do Whistler I recommend staying in the village and getting the whole experience, nightlife and what not.
In addition to Whistler, Baker is another place to hit (depending on conditions, as someone else has said). Bellingham (about 1.5 hours north of Seattle) is pretty cheap to stay in and about an hour from the mountain. Baker can get pretty icy if it hasn't snowed in awhile. It's a lot smaller and known as more of a "local" mountain, no high speed chairs, smaller lift lines. Other mountains around here include Stevens Pass (2 hours from Seattle, decent terrain), Snoqualmie Pass (45 min from Seattle, rains all the time), and Crystal Mountain (2+ hours from Seattle, pretty good terrain).
Whistler is definitely not going to be the cheapest trip, but worth the price IMO (at least for one trip). Add a day or two at Baker and you've got yourself a pretty damn good trip.
Anyway, hope this helps!