Great service worth the extra cost (but allow plenty of time!).
The women at Sunny Smile are unfailingly friendly and do an excellent job with nails. The manicures (fill-ins) I get there last much longer than the ones I used to get elsewhere, so the few bucks more they charge are worth it. Since the manicures last longer, I go less often, and the cost comes out in the wash. Pedicures are also great there, with lovely big massage chairs and leisurely, painstaking pedis.
That said, Sunny Smile is NOT quick. Many mani/pedi spas in the city do high turnover, quick and dirty mani/pedis for their working crowd. Don't expect that here. Plan on spending some time at the salon and don't schedule yourself too tightly. It's worth the time but it can be frustrating if you're on your lunch hour.