I am probably the pickiest and most over protective dog owner in the St. Louis area.
That said, Sebastien's is the absolute best. Clean, open floor plan, informative staff, huge kennels with windows so the pets can watch people come and go. They layout allows you to sit and watch your pet being groomed. Huge waiting area with comfy couches, flat panel television, teas and coffees.
I could possibly be jealous that my shitzu has a better please to have her hair done than I do... :)
Try it once, you will never go to another groomer.