My kids love Phineas and Ferb and have watched every episode multiple times. They have been disappointed that they don't yet appear in the parks. Last spring P&F were the only characters my DS9 actually wanted to get his picture take with.
Hopefully they will find their way out more often now that they have made their big appearance.
(For those of you who haven't watched P&F, it really is a pretty entertaining cartoon. I especially like when they poke fun at bad '70s TV shows).