1- One Stop on 12th is a great little shop. Ask for John, he's the owner or Sean. If nothing else, go in there. A real ski shop! Tell John, Ron sent you.
2- Sportstalker (Christy's) it's right at the Gondi/base area. Easier to switch out if you are demoing.
3- Terry Sports at Torian, at the base as well. Good folks.
4- Demo Yurt at the top of Thunderhead. They have Nordica and K2. Easy to switch in/out.
5- I think there's "Black tie" and "Door-2-Door". convenient but I am not sure of the quality and selection of skis.
I used Door 2 Door last spring. I rented their "performance" package, and it was fine. They and black tie will actually bring the equipment to you for fitting at your hotel/condo, which was incredibly convenient. They let you store the skis overnight at Sports Stalker at the base, which is also convenient.
There are overnight lockers that fit boots, so we ended up just leaving all of the equipment at the mountain every night.
I highly recommend Ski Haus between the mountain and downtown. If you do not have a car, the shuttle will take you there. I know they have Rossi, K2, Nordica, and Salomon. There prices are $36/day for demo whereas sportstalker are $54/day for demo. Plus, Ski Haus is a friendly staff.
another consideration is how many days one rents. most knock off 20%+ if more than 3/4 days ... also, i've found Christies (though i bought skies at One Stop and tunes at Ski Haus - which has a liquor store too) will barter if you call them ahead of time. though 3 yrs ago, my daughters rented skis for the week (6 days) at only $60 bucks, this was vrs normal prices of $15 -$16 a day for kids or ~30%