Great service, cheerful waitresses and prompt service, with a beautiful view. The tea lounge is located on the 23rd floor of the Mandarin Oriental hotel. Definitely check out the Amore Patisserie downstairs if you like their jams and would like to purchase some ($2 a small jar). Also the place is more expensive than the Four Seasons for afternoon tea.
The place has a nice section of tea, comparable to the Four Seasons, however, the teas are more Asian. There afternoon tea is daily from 3-5p. I had the decaf Illy coffee this time around and man was it good. As for the desserts, I personally like their croissants the best with scones coming in at a close second. I thought their Devonshire cream was only ok, but their strawberry was very, very good. The portions are somewhat small for the prices but nevertheless it is worth it every once in a while. Unfortunately wifi is not free but I can still sit there a couple of hours on end just admiring the view.
I would definitely recommend going if you have the time to lounge in Sin City.