keep in mind with disney visa you can get a 10% discount on a purchase over $50 but not with the rewards card. if the whole card is for nothing but souvenirs then you prolly wont put anything on your c.c. so go ahead and use the reward card for it all.
last year i went for the first time and loaded up the card and then saved it to use on a big purchase. when i found out i was paying out of pocket for little things all week and was not about to get my 10% b/c i was using the reward card i was annoyed. this year i first used my points to pay off part of the trip. i then made two big purchases while there to get my 10% off and then saved my reward card for photopass pics once home with the leftover points instead of buying souvenirs with it.