I was a little afraid to visit Sassafraz on a Friday night, but we had no problem getting a table, and I wasn't asked to leave when I showed up in my casual attire (I hadn't planned on going to Yorkville).
My Cosmopolitan was delicious and strong. The drinks menu had quite a few fun, creative options. We were starving so we shared a few appetizers (tuna and foie gras) and though the portions were small, both dishes were delicious.
The bar was quiet enough for conversation and the service was great. The décor is beautiful, even in the washrooms.
Sassafraz is a little pricey for my wallet, but nice if you want to treat yourself.