The gift vouchers and show bags are a good idea, but the bikes might be a bit big. That would mean someone from the committee would have to pack them along with all their own camping gear limiting there space for there own stuff.
Chocolate and lollies always work well on kids too.
I agree .. .Chocolate and lollies are a lot easier to cart to muster than 'big stuff', and its easier to distribute more smaller stuff to the kids, rather than one kid getting one 'big' prize.
I thinks we load the kids up with chocolate and sugar and keep them 'high' for the muster - they'll burn off the energy by chasing each other around.