Dont go to TTR for a nice beach. You'll be sorely disappointed. There is water, there is sand, but there arent any waves and the water is FULL of seaweed. You have to go farther south to start seeing the pristine beaches. From Playa Del Carmen on down, the beaches are as beautiful as any in the world IMO. Other than not having a decent beach. you'll have a GREAT TIME!!
Absolutely USA Transfers is the way to go. It's $55 round trip..... just the two of you in the van. They are right there waiting for you when you walk out of the terminal. When you get your bags from Customs, simply walk out of the terminal and don't let anyone help you with your bags or help you to find your transfer (it will just slow you down and likely cost you money). "Run the gantlet" as we say and just head outside... a USA Transfers person will be there holding a sign. Give him your name and he will have a van there for you within a couple of minutes. On our last trip (Nov 2013) we landed at 11:55 am and we were checked in at Temptation at 12:40. No worries on the return to the airport..... they are always there to pick you up at the resort precisely when they say they will.
While you're waiting for your van to arrive you will have just enough time to grab a couple of to-go-beverages from the beer cart that is nearby...makes the quick drive that much quicker! We only used our included transfer the first year...we've been using USA Transfers ever since. D