I feel that I really must defend Varadero here, as it seems that knocking it is a favorite sport on this thread. Having been to Varadero (against MY wishes at the time) as well as elsewhere in Cuba (incl. Habana), I have to say that it is one of the most beautiful beaches in the world. The Cubans there (though certainly not representative of the "average" Cuban) are also very friendly. Some of you forget that many people want a portion of their holiday where all they have to do is relax in beautiful surroundings without having to worry about money or where their next meal is coming from.
Although I am very grateful that I didn't spend my whole time in Varadero, it is nonetheless a lovely destination with friendly people and great beauty. I also found that other guests there came from all over the world (not just one or 2 countries) and covered all age spans, from kids to 20-somethings to older folk. Those who wanted "party time" found it with no trouble whatsoever.
All in all, if you are tired from working Mon - Fri. and want some "down time" to just relax, Varadero is a perfect choice. Pair that with some time in Habana and perhaps another centre, and you have a perfectly rounded vacation.

Besides the problem of coordinating what four people want to do, your other problem is the amount of time you have.
Of course Santiago is worth a visit, and if you are there, of course, Baracoa is worth a visit, as is Bayamo and Santo Domingo, etc.
If you read back through old posts, with ONLY TWO WEEKS, it is usually suggested that you do EITHER the western half of the island, OR the eastern side. Of course, if you are the type of traveller who wants to visit as many places as possible, without IMO getting a real feeling for any of them, you can do it all. But, at least for me, less than 2 or 3 days in one place does not even warrant going there.
My "advice" in Post #1 still stands :-)

I agree with poster 10 about Varadero. If you are a group of 4 with only 2 weeks, then contrast will be the best plan when choosing destinations. My vote is for Havana, Varadero, Trinidad, Vinales, Havana as an itinerary. Save Santiago/Baracoa for your next trip focussing on the Eastern end of the Island (in the winter months).

Yes, definitely, one end of the island or the other--not both. And as your flying into Havana, and others in your group want to go to Varadero, then I would say that that pretty much narrows it down to the Western end of Cuba; specifically, the four places mentioned by Poster #13.
Cayo Las Brujas is impossibly far away from Havana--7 or 8 hours by rental car. (You can't get there all the way by bus.)
If you have your heart set on an offshore island, then Cayo Levisa is your best bet. It lies just off the north coast, about 2 hours west of Havana. You can arrange a day trip there (try the desk of any big hotel in Havana), or, alternatively, you can take the bus to Vinales for a night, then a taxi to the dock where you'd catch the boat to Cayo Levisa--this two hours from Vinales. Overnight on the cayo in one of the cottages on the beach, and next morning return to the mainland and take a taxi the remaining two hour to Havana.
All this you could probably figure out for yourself if you had a map of Cuba, or had used the Virtual Tour map shown on the FAQ, right? Just to give you a sense of where places are in relation to each other, and how long it takes to get from one to the other. Like--why would you drive 7 or 8 hours each way to get to Cayo Las Brujas when there's Cayo Levisa, not much different, just two hours from Havana and, if you go to Vinales, you could pass right by it?