Went to Cuba a few years back, stayed in Cayo Coco (iirc) which is the touristy part with the hotel resorts. Lovely place, the hotel areas are great, we only ever left the hotel to go on the trips they organized, of which there are plently to choose from. We swam with dolphins and went on a scuba diving trip, which i think cost about $40 per person which was around £25 at the time, we also went to Havana and some other large city i cant remember the name of.
At the time we went they accepted US dollars, but i believe thats changed now to their native currency, however theres not much shopping to do outside of the resorts as its a very poor country, most of our money was spent on tips for the hotel staff and the day trips.
If you visit Havana or anywhere like that, you will get hounded by the poorer people for money or belongings, so its worthwhile getting a packet of pens and cheap notepads before you go to give to them. Also theres the odd cigar "salemen" who will badger you relentlessly and people who will draw crappy pictures of you and not leave you alone until you buy if off them for a dollar. Its all in good fun though its not like they're dangerous or anything, they'll just try to be your best buddy until they get what they want
Theres no shortage of things to see or do, but like i said most of our time was spent at the hotel. We went all inclusive which was great, but the hotel we stayed at was quite large and very touristy, id suggest if your budget allowed to splash out on a nicer hotel which will hopefully not be full of kids.
Oh and look out over Florida at night for lightning storms, amazing sight
