I went to Banff with a group of friends, and we wanted to have a spa outing together too. I looked for a place that was close by to the hotel (we were staying at Fox Hotel & Suites in downtown), massages/facials <$90, and could accommodate 7 people around the same time.
Yay for Pleiades. They were able to take us in a 2-hour block (some of us were getting 2-hour treatments; others were getting 1-hour treatments), and since their Mtn Ave. location was in the same building as Banff Upper Hot Springs, the rest of us were able to take advantage of the hot springs during the downtime. They gave us a free pass to the hot springs with access to towels and lockers (for folks off the street, hot spring admission is $7 plus a few bucks for towels and locker rental). The hot spring was crowded but I definitely wasn't complaining since it was free and convenient. If you forget your bathing suit, they have ones to buy (maybe even rent, I'm not sure).
The building is a little tricky to find the first time so just leave a little more time at the beginning to find it or get some really great directions. The only drawback was that they had told us that if we didn't want to go to the hot springs, we could go to the cafe upstairs to wait on the others. But the cafe closed at 6pm (our appointments started at 6). It wasn't a big deal for us though, but just FYI.
Overall, my friends and I really enjoyed our treatments. We got everything from reflexology to massages to facials. I got a 1-hour massage from Luke (I think was his name)... awesome! It was really easy to coordinate with them (almost too good to be true) and they didn't require a deposit or anything except my name and number even though I was booking 7 appointments! I highly recommend this place and would go back if I visit Banff again.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.