Here's coming from the dreaded phone company (I have the displeasure of working for one):
Any calling card call made from a payphone is going to have a surcharge. That's the way the company who owns the phone gets compensated when you are using someone elses calling card.
Calls from hotels vary. It depends on the hotel on whether or not they charge you a surcharge to make a call, whether it be local, toll, calling card, etc. The norm is around .75 per call.
Do NOT use a calling card from your "friendly local phone company." For example, say you're calling from Florida (Verizon territory) to Pennsylvania (also Verizon territory). Even though Verizon serves both areas, per current federal regulation, they are not allowed to connect the call using Verizon equipment, lines, etc. The call will go through whatever long distance company serves the hotel, usually AT&T, Sprint, or WorldCom. These calling cards calls are usually very high in price. I have seen as high as $9 for a one minute call. That's an exception, but the per minute and surcharges are still very high.
Your best bet (unless you have a cell phone with nationwide calling included) is to buy an AT&T pre-paid calling card from Sam's Club. These are cheaper and a better deal calling wise than the comparable card from Wal Mart. I don't have a Sam's membership, but had a co-worker pick up one for me. Don't throw the card away, they can be recharged with a credit card for 3.7 cents per minute. There are no surcharges on this particular card, except for the payphone fee. Plus, as I mentioned before, Disney may charge you a small charge. If you can't get ahold of a Sam's Club AT&T calling card, try picking up another pre paid one, but keep in mind that sometimes the surcharges are really high. Still, it's usually better than the alternative.
Hope this info helps someone out there.