I just looked through the Guide books from past years and I can't think of anything that is an extra charge- except for the Mothers Day Brunch.
For many years I have been a "Flower Power" concert fan. Keep in mind that sometimes the headliners at the concerts change for one reason or another. Here's the current schedule and my reviews from past appearances...
Flower & Garden Festival (April 5-June 3, 2007)
The Buckinghams April 15-18
(Excellent show!)
The Turtles feat. Flo & Eddie April 19-21
(Always a lot of fun!)
The Box Tops Feat. Alex Chilton April 22-24
(New this year!)
Petula Clark May 4-5
(Also new this year and should be great!)
Davy Jones May 11-15
(Always big crowds for this one!)
B.J. Thomas May 16-17
(Not my favorite show)
The Grass Roots starring Rob Grill May 20-21
(Rob is a homey- I'll be there!)
Gary Puckett May 28-30
(Don't miss this one!)
Herman's Hermits Starring Peter Noone May 31-June 3
(Always long lines for this guy!)
I always enjoy looking through the theme merchandise and artist offerings at the Festival Welcome Center- Innoventions West. Last year, my favorite "local" photographer had a beautiful display of large panoramic art-
http://stevevaughn.com/intro.htm
David Doss and and Larry Dotson usually are there as well, with many other outstanding artists.
For everyone in cold weather states- Flower & Garden is one of the best times to visit WDW. It will be like "instant summer" so be sure and bring your own sun screen!