One thing you really don't want to eat when you're in Cuba is a hamburger. They are, seriously, the most disgusting things I have ever eaten. Don't be sucked in by the 1CUC price, they are nasty, awful, yucky. There is really a lot better food to be had in Cuba than a hamburger.
One caveat: Some of the burgers at the resorts are edible, if a little chewy and tasteless. The hamburguesas you will find off your resort, at the street vendors, are the ones that are really bad. The worst one I tasted was at the airport - you don't have much of a selection at the restaurant in the airport. I learned on my next trip home that your best bet for food at the airport is a pizza or a tuna sandwich.
Trust me on this one.
My parents just returned from a 2 week trip to Varadero where they stayed at the Mercure Cuatro Palmas. I was VERY excited for them since I loved Cuba when I was there but they actually had a lot of very bad experiences and the El Rancho restaurant on 62nd seems to top it:
The waiter put a bottle of wine down on the table and before allowing him to open it, my mother asked him how much it was. He told her it was $8.70. She repeated the price, he confirmed it and then she let him open it. They never showed them a wine list. When the bill came, they charged them $87.00!!!! My parents argued with the waiter about this and he refused to concede and called the police. The police came and threatened to take my parents to immigration if they did not pay this OUTRAGEOUS price for the wine, even after being lied to. They responded, "You are in Cuba now." This kind of behaviour is COMPLETELY UNACCEPTABLE, unethical and illegal. DO NOT SUPPORT this restaurant. My parents later found out that this scheme happened to at least one other couple who had eaten at the restaurant that same night.
Booze flows more freely than water in Varadero (it's cheaper too), so take it from someone who learned the hard way. You don't have to drink it all in one day!