I vote for AK. I'm going on the assumption that all the rooms are connected to the lobby/main building and that people aren't walking around the preserve to individual buildings.
With an 18 month old, when you need (cheerios, diapers, milk, socks, stickers) or when they're napping and you need (water, book, beer) and God forbid it's (raining, hot), I'd rather have everything central than take a 10 minute walk.
I've stayed at CBR, and even as a twenty-something I remember the walk to the buses being a bit long...forget it with a loaded stroller.
Have fun!