These are all such good ideas -- I wish I had been thinking about this sooner, i.e. before they left! I did get them a lanyard and gave them a couple pins to take with them to trade.
Also, they're staying at Coronado Springs, so I called guest services a while ago and they're going to alert housekeeping to do some special services, like folding their towels into animal shapes or something, she said. They also said I could fax a message to their front desk 'from Mickey' and they would deliver it to their room!
Keep the good ideas coming -- I could still do something tomorrow!
Loyally,
Tiggerjan