i been to one where they had a disco room with flashing lights and music and a games console area - maybe it was the same one?
lockers for handbags, purses etc i always have to make sure i wear trousers with large pockets cos i don't want to leave it unattended when i go on the equipment with ds. a buggy park could be useful too.
ds loves those huge car mats too. he spends ages playing with those. my friend goes to one with trampolines which sound fun. ours has a supervised messy area where you can do painting, pottery, playdough, colouring, drawing, cutting and sticking etc.
a big play pen where you can put younger babies would be good. i hate it when ds crawls off and i am trying to drink my drink. more than once i've jumped up in alarm to rescue him and knocked it all over me.
i mentioned big leather sofas earlier but forgot about the big leather beanbags. they are to die for!!
obvious essentials are lots of parking, lots of easy to clean high chairs and play gyms for younger babies, low sinks and toilets for littlies, empty nappy bin regularly - ours has one of those nappy wrappers and it hardly ever smells and if it does if you tell them they empty it immediately.
a gift shop that sells little crafty items will bring extra money in.
never been to one with wi-fi but i would love it if you got free wi-fi access like in wetherspoons/starbucks.