We typically take different routes there and back. I find things to do or see along the route. Sometimes it is our rest stop or is near where we stop for the night. There is so much to see in Co., AZ and UT and between there and Florida. If you have some places in mind that is a start. I would look at the state tourism sites, Trip Advisor, etc to see what might be interesting.
It is a long haul out there. Just a thought but it may be more relaxing to do week one as a base camp, week two move around, and week three as a base camp before you head home. X2 on finding some higher elevations to visit.
If you let us know the ages of your children; your interests; dog, etc we could provide better ideas.