We flew from Gatwick on one of First Choice's newly refurbished 767s, and very nice it was too. Decent choice of films (8) with the option of "upgrading" for a fiver, which got you another 4 films, plus you could start them when you wanted (plus pause, fast forward, etc.). Less impressed with the TV side, as I felt the choices were a bit dated. The flight was fine, and the transfer was handled very efficiently.
We'd had our hotel changed by First Choice due to "storm damage" from Hurricane Emily, and were unsure what to expect - especially when the coach turned into a tiny side street.
Not to worry though, from the first step into the air conditioned, marble floored lounge, to the final goodbyes 2 weeks later, all the staff (and I do mean all) became personal friends as they tried to meet every little need we had - not always possible, but they tried. For example, the hotel we booked had a fridge in the room, which was necessary to us as my wife is diabetic. We explained the problem to the manager (his son is also diabetic) and a fridge was brought round to the room. Ditto Diet Coke - the hotel doesn't stock it, but they arranged for 4 cans a day to be brought to our room, and made sure the bars all had a bottle or 2 in their fridges.
The rooms were quite spacious, with a queen sized bed, then 2 steps down to a "lounge" area, with a single sofa bed, and the double patio doors. The floor was "marble" tiles and the individually controlled aircon wasn't too noisy. The food was well cooked and well presented, but like all hotels offering 2 buffets a day it got a bit samey; there was also an a la carte menu available, which made a nice change, and lobster & T-bones were available at a supplement.
The evening entertainment was poor in the main, and although the animation team worked really hard, they were better suited to pool games during the day. The pool area was very good, with a decent sized main pool (with swim up bar), a poolside Jacuzzi, a kids pool, and a separate water slide. There was also a "quiet" (adults only) pool away from all the other pools.
There was also a daily courtesy bus to the City Beach Club, which is about 6 Km away, and is excellent. As well as the beach, there are loungers, a bar/restaurant and a water slide. The bus goes at 10, and brings you back about 3.
Excursions/trips:
Chichen Itza was the only trip we booked through the rep, and it was an excellent day out, with stops at a Mayan market and a cenote (for swimming) before arriving at the pyramids - stunning! We had a guided tour fro about an hour & a half, then the same again as free time, and we didn't see everything, as the site is quite spread out. There are a number of refreshment areas scattered around, which was good as the site is quite exposed. Another good thing was that the guide had free water & soft drinks available all the time on the bus, and he made sure we all got a bottle of water before we entered Chichen Itza.

We booked our trip to Xcaret direct from the website before we went (better exchange rate at the time, plus an online discount) and chose the dinner option for the evening show (see below). The company phoned us at our hotel the day before to confirm the pick up details, and on the day all went smoothly. The guide had our colour coded wristbands, and out dinner tickets, and made sure we checked in and reserved our table before turning us loose on the park for a great day out. My daughter & I chose to pay US$45 each to do the Sea Trek, where you walk on the sea bottom - worth every penny. On top of that, we snorkelled in the sea, rode the underground river, walked the jungle trail and sailed on a raft. We saw turtles and jaguars, deer and other animals, and had an excellent meal in the Mexican themed restaurant (one of 5 or 6 different places to eat). Having shopped for souvenirs and rested our weary legs, we made our way to the "theatre" for the show; because we had booked the dinner package, we were directed to our table, at one end of the arena (non diners were seated along the 2 long sides). If the 4 course dinner was better than we expected, the show was truly spectacular charting Mexican history from the Mayans up to today in a couple of hours of drama, music and dance.

We also went swimming with dolphins, which is offered by several places in and around Cancun. We went with the folks at Wet 'n' Wild, the water park, mainly because they offered swimming in the sea. If you are not a confident deep water swimmer, book through the aquarium or similar, as the water is shallower. After some basic instruction, into the water to pet the dolphins, have them kiss you, "shake hands" and swim with you. Photos and a DVD are available afterwards if you want them. This really is a lifetime moment.

A word of caution:
Many of the bars and clubs offer an "open bar" deal where you pay £25 to £40 to get in, then all drink is free. Not quite, I'm afraid. In most places the bar gets so busy it can take over an hour to get served, and almost without exception the bar staff will want a tip for every drink they serve - no tip, no drink!

If anyone has any questions about Cancun or anything else, just ask & I'll try to help.