well if i did know a secret place, i would have to tell you in secret :-) however unfortunatly i dont know any.
though, i can say that probably the best experiences you have will be unpredictable, and with cubans! they will tell you the secrets!
i was rather lucky to meet a cuban family who needed to visit their family down the south of the country and we travelled 2000km down the centre of the country and back which was nice, i payed for the petrol of course, which came to about 150 dollars but it was a good deal for me because they really showed me around. it was unforgettable really , i was very sad to say goodbye in the airport.
in the centre, away from the beaches there are not as many tourists,you could go to a small town and be lucky to find that its the festival week there. then you will see how the cubans party. also i was invited to a family party with some cubans in havana, where they did some unusual religious ceremony, i would recommend this kind of stuff.
as for landscape and beaches i didnt delve to far, i liked guardalavaca. and i had heard about cayo jutias, a remote paradise beach that apparently has no buildings or anything like that around, you can camp there apparently, i was on my way when a cold front came over cuba (mid january) and it was cloudy for a few days so i opted not to bother, as i think you really need the blue sky to show up the lovely blue waters.
i had done absolutely no research before going and had just heard a little about trinidads salsa scene and saw some pictures of piñar del rio area, so natrually i went to visit. trinidad though nice indeed, was not really what i had hoped, tourism is really the only thing propping up the place,and i get a little bored in places like that,
its true you can dance salsa 7 nights a weekin trinidad , however the main salsa venue though great fun is populated mainly by foreigners, while all the cubans actually party out the back to regaeton. but i would still recommend a visit, many repeat visitors will go literally straight there when they get to cuba and straight back.
one of the most enjoyable experiences for me was discovering a new incredibly talented bunch of musicians almost every day playing in some bar or on the street. i sat for hours on end listening and baught lots of cds, but thats just my kind of thing.
the best experiences will probably come un planned i guess, thats the excitement of travel.
you will love it