X
XP-37 space cruiser (vehicle on Buzz Lightyear ride)
doesn't start with X but Mexico in WS and 8-Trax in Pleasure Island
Y
Yacht Club
Yo Yo at Pop Century
Z
Zazu
Zurg
Zip a dee lady (name of rivwerboat in Splash Mountain)
another W
Winnie the Pooh
Hope these help. It is so funny because I was making this list the other night because we are going to do the same thing on our trip.