Friendly and welcoming atmosphere with no cliques for both kids and adults.
Music and physical activities to tire the kids out incorporating learning. Therefore, mini trampoline can be used to show how frogs jump and when the kids get on it they can show you how frogs jump, tunnels for them to go through and pretend they are snakes, climbing frames to be monkeys and so on.
Anything to keep them limber, get them excited about physical activity and start understanding how their body works.
As a mum I would like somewhere that had good quality coffee for the end of the session with a large seating area for us, kids and prams.
Oh yeah, ability to park prams easily whilst kids are playing. There is never enough room for prams generally.
Singing and dancing to be included as all kids love this and once again they are being physical and learning about their bodies, spacial awareness and so on.
Somewhere that encourages mums to join in.