Similar to what you said.
The Big fireworks displays tend to use either the 1812 or Handel's music for Fireworks for finales. Can't remember for certain, but sure they used the latter last year.
Might be worth checking that out.
Failing that, you could try a good music shop. they'd probably know the sort of thing you're looking for and you'd be able to listen to it. you wouldn't have to buy it would you? ;D ;D