Help - Where can a family of 3 go in January
for some nice warm weather ? We do not want
to leave the US - is there anywhere besides
Florida or Hawaii ??

Central or Southern Arizona, Las Vegas area or Palm Springs area.

Palm Springs is a good idea. Las Vegas on the other hand isn't necessarily a warm place in January. I was there this past Janaury and encountered a snow storm on the drive there from Southern California and needed a jacket for my entire 4 day stay.

You requested "NICE warm weather".
Nevada and Arizona do not qualify in my opinion. 62 degrees and dry does not feel nice and warm to me in January, though people from snow country might feel otherwise.
The only really warm place in the US in January is southern Florida. And that's still MOST of the time.