Some advice for you if you do get to Cuba--they do not accept American Express travellers cheques, or any cheques drawn on a US bank. The ironic thing is that they only accept US currency from foreigners. Wierd. Get some Canadian bank issued travellers cheques, and cash those if you need to.

As a Canadian, I go to Cuba often (once every couple of years) for vacation.

I have received questions from the INS when coming back to the US, questioning why I travelled there, and I respond with "great beaches, and fantastic coffee". It's never a problem for me. That said, if you are a foreigner, avoid getting an entry/exit stamp in your passport from Cuba, as it will just create more questions from the INS.