Well I think we can rule out anything Disney, Universal or Nickelodeon. I think Cartoon Network is also out with Ben 10. On a small scale I will say just one TV show - like Peppa Pig and Thomas the Tank. But what, I don't know.
I think some good choices are Fireman Sam, Teletubbies, Noddy, Postman Pat, Horrid Henry, Mr Men, Loony Tunes or Roary the Racing Car. All very popular and some might fit in with older children and not just the very young. Also some can easily fit the Metropolis theme and be next to Velocity - Noddy, Roary, Postman Pat and Fireman Sam can be themed as a mini town within Metropolis the city! Some good opportunities out there - I hope they make a good choice!
(They have had Postman Pat at the park so might be a good idea to utilise this more...)