A family member was kind enough to give us two generous $50. American Express gift cards for our 5 year wedding anniversary. Of course I want to tuck this away for our trip, in ONLY 18 DAYS BY THE WAY

, and I am a little nervous about them. I've never had an Amex credit card, nor ever used a Amex gift card.
Will these be widely accepted around the Disneyland Resort? At restaurants, for souveniers, etc?
Also, if I am making a purchase for MORE than the amount of the card do I have to tell the cashier the balance of my card so they can ring that amount?
I think we'll just use them for our dinner at Napa Rose. Do you think they'll give us trouble for using two seperate $50 ones?