Having tried several of its branches, I find HealthLand a bit too busy and commercial for my tastes. The lobbies are bustling with people, particularly on the weekend. Just look at the size of the parking lot out front; and it's usually full on the weekend. I need a more relaxed experience, right from the minute I walk into the place. I've been using
Lavana since I started coming to Bangkok. You'll find that the whole calm/soothing/peaceful thing starts as you walk in the door, with lighting, soft music, even the colors used in the décor.
Regardless of where you go, 600 baht for an hour should be AOK. For example, Lavana's website lists a one hour Thai massage at 550, 1˝ hours at 700 and two hours at 800.