Isn't that amazing?? I am no big fan of Universal or IoA, just can't imagine anyone refusing to go to Disney.
DH had an employee who was going to LIE to her son (5 years old) and tell him that Universal was WDW. DH convinced her to just take ONE day and go to WDW. She came back and absolutely LOVED WDW!! She's a convert now and a true believer!!
Maybe you could try the ONE DAY trick!!