All inclusive in Cuba usually covers everything except watersports like scuba diving and paragliding etc
It all depends on what you want to do when you get there
I went to Cuba 2 yrs ago and took a grand, which was spent on gifts and excursions
We went swimming with dolphins which was a full day by plane and on a speed boat excursion
Cuba is an amazing place, the best holiday we've ever had. There were three of us for 2 weeks and we took about a grand if my memory serves me right.
We went to the Cayo's
Beautiful place, lovely people
Do yourself a favour, and take some stuff like crayons, shampoo, pencils, toothpaste etc and give them to the cleaners and staff
They find it really hard to get suck basic stuff and really appreciate the little items, and it will show in the way they give you and your room special attention
Be careful if you are taking a credit card/. If it is an american company (like Capital one) it will not be accepted.
They have a special currency just for tourists, which is only supposed to be spend on the resort where you stay, but shops do take them.
Have a great time, and I'm as jealous as fuck