We have a 2 year old and a baby and both of them LOVE COSI. My 2 year old is generally shy and reserved and she runs off exploring the whole Kidspace area (good thing they have the door guarded). They have big blocks to build forts with, water tables, stuffed (fake) food, a play structure, a big birds nest, a ball pit, and much more. We have a pass and go to COSI once every couple weeks and the kids don't get tired of it.
Tip: park at the meters on the street. Although it's more of a walk, it's a lot cheaper than the parking lot.
PROS: Too numerous to name
CONS: Hard to get the kids to leave
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