If you don't have a dog, it should be somewhat easy to find a place. We found a place in Silverthorne that we're renting for 6 months (Nov-Apr) that is pretty sweet. Ours was a little harder working a dog into it, as most owners don't want to F with that.
I found it just cruising Craigslist every single day for new postings. Got to hop on them fast as there are a ton of other people doing the same thing. I must have emailed at least 150 people. Just refreshed craigslist every morning and you can tell which links you haven't already clicked on (because they are still blue).
Summit Daily - looks like you already know of this site. I actually posted my own Wanted listing on craigslist explaining our situation (group of weekend warriors, respectful / won't damage anything, etc.) and had a bunch of people email me with their options.
How much are you looking to spend? To find a 2 bedroom place, you're looking at probably $1300 minimum (that was about the cheapest I found for 2 bed) for a 6 month lease. We went with a 3 bedroom place (1 queen, 2 full, 2 twins, 2 couches) that runs $2200 month.