I guess it all depends on the costume, or the setting, the time of day and/or which land would you work in. Factor in all of that and your own thoughts about which attraction you would love to work at for the summer.
If I lived close by, had gotten a job and had to choice to pick a Disneyland attraction to work in, I would love to work at The Haunted Mansion.
If you'd like, go ahead and include DCA attractions into this thread. ;o)
Over at DCA, I'd love to also work at Tower of Terror. Mabye I choose both scary rides because I just adore All Hallow's Eve. ;o)