Your ticket allows you access all day as many times.

The 5 year old for sure and probably the 11 year old as well will be absolutely delighted with the "water room"--I call it. The kids put on yellow rain slickers and "play" with water wheels, water falls, every kind of water play you can imagine. I love to just watch the kids because of course they can't refrain from giving their sister a squirt. It's all great fun and they are covered so can splash to their hearts content. Of course some areas like shopping in the grocery store will be most appealing to the younger kids, but there is plenty of options for the older kids while the little ones shop. My sister taught first grade for 36 years (I taught Jr. College), so I have gone with her students an many field trips. The Children's Museum at Navy Pier would host us by ourselves to check things out. There is another fabulous Children's Museum in the far north suburbs, but if you are staying downtown, this Navy Pier Children's Museum will be great for the children whose ages you mentioned--and I think the adults will have a good time watching the kids and they adventure to learn new things. Have Fun!! Elizabeth (I can look out my window and see you there at Navy Pier. Be sure to wave at me--Ha!)

They have a coat room where you just hang up your coat. No attendant, no charge.

I think 2-3 hours is plenty of time. Especially with the older kids, they move through activities faster than toddlers. I think we were there an hour and a half with our 3 year old and we ended up cajoling her to leave. The museum is on Navy Pier and there are lots of things to look at there. Carnival rides, a lot of good restaurants, boat rides.

There is also a big room where you can park the stroller/gear. It's not supervised/locked if that matters to you. Keep in mind also that the staff can/will grab your stroller and put it in this big room if there are too many near the door or you are blocking the walkways so look there first if you happen to "lose" your stroller. Have fun!