Definitely do Dumbo
First! The lines for Dumbo can get awfully long- and unbearable when you're toting little ones with you!
I'd say: Do Dumbo First thing in the morning, Check the lines at Pan and Goofini (previously Barnstormer)- if both are short-
ride Goofini before Pan (it has become more popular than the latter)- then Ride Pan afterwards.
If the line at Peter Pan is looking like it could be long by the time you finish Goofini- grab a Fastpass, ride the Goofini (twice maybe) and then head over to Peter Pan and bypass the line!
Enjoy!