I like to surprise my family with an extra special PS for a restaurant I know they'll like, and sometimes I'll order a really good dessert for us to share! If I saw my teens looking at a special souvenir that they might not have enough money for, I'll buy it for them as a surprise for later at the hotel!
For my youngest DD, last year we did a "Mommy & Me" trip (DH did come too) and I had arranged for Disney Florist to bring a Mickey basket with camera, autograph book, pen, balloons, stuffed Mickey, etc.
For our trip in December, I am planning to have a "surprise" package waiting for her in the room every evening - I'll pack the bags and tissue to bring with us, and DH will distract her in the gift shop while I set it up in the room. I bought some pins for trading, some special pajamas, I'll pick up a stuffed animal for her, etc.
Can't wait for December!!! By the way, we'll be at Pop Century too!