My wife and I had a blast at the Dunes (Doo-nez) over Christmas and New Years (1st time, we're around 45). We were at building 36 which is beside the main entrance, but we usually walked instead of taking the trolley (5 min turnaround for the bus, 7 minute walk). The room was fine and clean (hardly there), we left tips every now and then, 5000 bs. At the end of our two weeks our legs were sore from climbing the three floors of steps.
The grounds are pristine other than the 300+ rooms they're building right now. The food in our opinion was excellent, there was a good variety all week long (themed), but even when they started over the next week, there was something different.
Luciano's, the al a carte restaurant, has the best tomato soup known to mankind. The very good selection of appetizers and entree's was impressive. The Christmas Eve and New Years Eve parties were great.
I found the liquor better than in Cuba and Mexico. The beer was similar and tasted watered down compared to Canadian beer (my standard).
We met two fabulous couples, one from Canada and another from Sweden whom we spent the majority of our time, other than the great Jeep safari we went on with a guy named Luis.
The vacation is quite cheap once you get here, as long as you change your US$ on the beach or at a flea market (you get asked all the time). You end up getting double+ the bank or hotel rates of exchange. The jeep safari ended up costing $25 US for a 9 hour day.
The staff was fantastic and looked after all our needs. Francisco at the breakfast/lunch (main) restaurant was especially accomodating, great guy.
We intend on going back to the Dunes next Christmas and New Years but with more family this time.