Coincidently, we are in exactly the same position as you. Only we are retired, and our kids are long gone. We also want to sell our 13' Scamp and trade up to a 17'. We want to wait for warmer weather to do this, I think.
I too started out considering a 16'. But there are significant differences between a 16' and 17' Casita
. ie The refrigerator
in a 17' is about twice as big, and has a freezer. The bed is 54" wide vs 46" for the 16" (the Scamp bed is ~ 43"). Interior height is 5"10" for the 16' vs 6'2" for the 17'. 16' has no screen door, 17' has a screen door. This info is from their current catalogue and website. It may vary in older models. Of course the 17' weighs more than the 16' (240# more for Standard, and 295# more for Deluxe, and 40# more for hitch. All dry weight
, and all from Casita
specs). And you'll need a class 111 hitch for the 17'.
It all depends on your own priorities, but I went thru this investigation, and felt compelled to offer the results of my exploration, and save you some time.
Hope this helps,