If you mean you're off to Walt Disney World in Orlando, can I reassure that US Dollar travellers cheques are accepted as cash almost everywhere. We never had to show ID, either.
The only places which didn't guarantee to take them were the carts selling water, ice cream etc - some did, some didn't. Also, you'll need a bit of cash for the toll roads when you first arrive.
We just took a bit of cash to see us through the first day, then stuck with travellers cheques - you'll be given change in dollars, so you'll soon have cash in your wallet as well!
Have a great time there!