Ely Cathedral was fantastic. The key to its success was to keep it fast-paced and fun. And a way of calming the children down if they got over-excited! The entertainers used a series of silly poses he got the kids to take.
All the children were in a big group on the floor. Parents were mainly sitting at the back of the group, rather than amongst the kids. Age range was 5-11, although there were a few toddlers as well.
There were a number of groups involved:
GenR8
John Hardwick
I reckon that our suffragan bishop has missed his vocation as a children's entertainer
There were puppets (our diocesan resource centre hires these out for free - may be worth checking whether you can borrow some), sketches, games and worship songs, all backed by a big screen showing what was going on (including the words of the worship songs). The worship songs were all action ones.
Obviously, this is on a big scale, but its worth seeing what ideas you can nick. I took some photos - haven't got round to putting them up online, I can do this, if you're interested...