We always put a credit card on our room key and then charge everything to that in the parks. We don't find a need for Travelers Checks. We usually pay off the room charge at the end of the week with our debit card so that it doesn't go through to the credit card. It is so nice to only worry about carrying our room keys and a very small amount of cash in the parks. For example, last year we anticipated needing $500 for meals and souvenirs. Our charges came to $650, so we paid the $500 at the end of the week and let the $150 go through to the credit card. It is nice to have one itemized bill at the end of the week, plus have most of purchases paid off before we leave instead of getting a huge credit card bill. We usually only take a $100 or so in cash for the few snack stands in the park that don't take cards.
However, now that I have the Disney Visa, I will probably just let everything hit my charge card so that I can earn the reward dollars. Hope this helps.