Hello Angela and thanks for returning to the Disney Parks Moms Panel with yet another great question and be assured we Moms & Dads all love helping awesome Guests just like you!
Wow you've really made some delicious choices of restaurants to enjoy during your holiday this coming August to Walt Disney World Resort; all of those would definitely make my own families top 10 must-do dining locations.
Although I tend not to use Travellers Cheques these days I see according to this
Travel Advice page found on the UK Disney holidays website that
yes Guests most certainly can still use Travellers Cheques in place of cash at most USA outlets.
However since the Travellers Cheques were issued back in 2009 I would double check with the original bank of issue just to be absolutely, positively sure the cheques are still valid for use and don't need to be re-newed!
I thought you may also find this
Banking Services link to be an extra useful planning resource.
Have a great Disney day.
~ Jane