I can't comment on the spa services, but the yoga studio at Tula South is really fantastic!
I am in Toronto for work, and have been attending classes a few times a week here for about 3 months. There are two studios (one heated one regular), and the space is quiet, clean, and presents a very calm energy. Exactly what I want in a yoga studio.
I've taken the Hot Hatha and Hot Power Flow classes with several instructors. All of the instructors I've had gave clear guidance and adjustments, though Elizabeth is my favorite! I attend classes after work, and class sizes are typically small with lots of personal space for everyone. Class difficulty is generally tailored to the skill level of those attending - but there are always easier/more challenging variations on the poses offered for those who need it.
Love love love Tula South! I will be sad to leave it when my project in Toronto is over.