My girlfriends and I love the Spa at the St. Julienne. We've received good service there and the atmosphere and entire pool, hot tub and lounge areas are fabulous. My massage with Pax was excellent. I recommend it to anyone who wants a relaxing day without having to go far.
While I've never stayed in any of the rooms, I've toured them and they beautiful.
Also, you can't beat the lobby, lounge area. Great live music, cool fireplace, swanky bar, etc. Definitely check it out if you live in Boulder!