Entertaining very young children in Stuttgart

I have family visiting me here in Stuttgart for a week with 2 small english speaking children (2 & 4).

I realised I have lots of options for making sure they are entertained if the weather is good eg. Wilhelma (though I suspect we will go here whatever the weather), Ludwigsburg looked nice, and there are some theme parks around that are also options. I'm less well prepared if the weather is really poor - could anyone suggest any options? I've not managed to get to any of the galleries/museums yet (strike me down!) - are any of them suitable for a 2 and 4 year old?? Eg Natural History?

Also any pleasant city centre eating options that cater for kids with food and seating etc. Oh and anywhere which has a play pen would be an option, in case us adults want to take it slowly.

All recommendations gratefully received...

This place may appeal to the 4 year old, the 2 year old is probably too young to appreciate most things for more than a few minutes!! It's in Sindelfingen/Boblingen and is an indoor adventure/learning park called Sensapolis

Tripsdrill is also a nice fun park specifically for younger kids and they have a nice petting zoo and animal section there too.

Thanks for the tip Nicole - I hadn't heard of Sensapolis before. Tripsdrill was something I was considering too.

Still not sure about food options... any suggestions anyone?? Or does Germany generally cater for the under 5's pretty well in restaurants? Not sure myself, as I've never had a small child accessory when I've been out and about...