Me, Hubby and kids (21, 17, 9) are going to US for 3 wks at Xmas, any ideas for great itineraries. Land in LA?

We would like to include NY, Vegas and Anaheim, but would like to add in another stop that is really interesting, for us all. Last trip we went to all of the above as well as Chicago, San Fran, Memphis and Milwaukee. We loved the fact that Milwaukee and Memphis were less touristy and more like what we imagine America to be (we're Aussies, but don't hold that against us) :-) We don't know what sports are still on over the Xmas period that we could maybe get seats at and if it will be too cold to go to certain places, we certainly don't mind the cold as long as the location is not really doable because of snow. Any advice would be fantastic and greatly appreciated.