Exhale at Hotel Palomar is nice. Also, Spa at the Hotel Crescent. If you are in North Dallas the Grand Spa at Beltline and the Tollway is good as well. Spa Nordstrom at the Galleria is small but nice as well. HTH.
I'm a regular at Bliss in LA. I adore them, but they can get expensive...I generally prefer Bliss for massages and manis/pedis. I like the facials, but I can get better ones for the money at other spas.
ETA: If you get waxing done, Bliss is really awesome for that...their Poetic Wax is near-painless. I also spend WAY too much at the store in the spa.
favorite treatments:
'double choc' pedicure
the full monty (brazilian bikini wax)
blissage 75 (they do a really good job training all their masseuses)
the ginger rub (you have to love ginger, but it smells sooooo good if you do)