We took our then 4yo daughter and 1yo daughter to the Kalahari Resort in the Dells a few years back. I too had worries that they were too young but we were blown away at how baby/toddler friendly this resort was! It had a couple huge toddler areas w/ little slides, water spouts, treehouse, etc. My girls were in heaven! They also had a huge wave pool and lazy river that we took advantage of (I held my 1 yo in my lap on the tube and she loved it!). We also went during the fall and got a very reasonable rate that included waterpark admission. The room was HUGE and very child-friendly, we were very happy! The only obvious minus to going to the Dells in the non-summer months is there are a lot of attractions that are closed (like the big outdoor waterparks and amusement parks) but w/ such small children we would have been unable to enjoy those big ride w/ them anyways. We did find go-karts, mini golf, and the Ducks (those water/land vehicle things that the kids LOVE) were all open. Also the fall color on the trees was gorgeous, so it made for a beautiful little road trip. We are actually thinking of going again this fall w/ our now 3 kids (ages 7, 4 and 2.) I highly recommend it! Have fun!:)