Rhumbar is one of the only on-Strip bars I would ever care to visit and naturally I discovered it less than 3 weeks before I am moving away.
At night it probably has a more clubby and douchey atmosphere but during the day it felt like I was relaxing on the beach instead of on a patio outside the Mirage. There are misters to keep you cool in the sun and a combination of shady and sunny places to sit, relax and have a couple of tiki drinks! I was surprised to see that they have hookah as well.
My only complaint is the service... our drinks took FOREVER to arrive and our waitress was less-than-attentive and mildly bitchy. It didn't detract from the enjoyable atmosphere and general yummyness, though.
The pineapple chipotle margarita is great!