I live locally and received a gift card to the spa. I had been to the hotel for various events and it is very beautiful with wonderful service. It is definitely for a higher end experience but still a little of the down to earth vibe that is Colorado and Boulder. I will admit that I wondered if the spa treatments would live up to the hype or if it would be posh for posh's sake. I can absolutely tell you that if you are looking for a first class class service the St Julien delivers. I have been to spas around the world and this one can definitely compete. The facilities are beautiful, well maintained and constantly checked. The spa is small, so I did find the changing area a bit cramped when there was a party of about 6 other guests present. Not really conducive to lounging and relaxing. However, when they left it was just fine. Use of the small fitness center. Hot tub, lap pool (approx two lanes unmarked), steam room, dry sauna are included. I did take time to partake of them all. My services with Eric were exceptional. He clearly knows what he is doing and is the ultimate professional. I had they High C treatment and a massage. I often get treatments that in some way left me wanting more. Not necessarily a bad service, just something missing. Both of my treatments left me completely content. The $5 valet parking is a very nice touch as well.
You can likely get a fine massage or treatment for less in the area, but if you truly want an exceptional all-around experience, I would definitely recommend the St Julien.