Well my ultimate job would be in merchandise at the Emporium because the way I see it it's always packed so I'll always be busy plus the day will fly by. Plus I get to interact with all the happy/not-so-happy visitors. The latter I'm not really looking forward too but it will make my day more interesting! XD
But really anywhere on Main Street would be great and then anywhere on the main street of MGM and then Mouse Gear at Epcot. If NOTHING full time in merchandise then I'll try for attractions at MK!