We houseboated for nine summers in a row.
Don't forget to add food, beer, gas for houseboat, gas for boat, gas for jet skis (if you have them) gas to get there, gas to get back.
And if it's far enough away, overnight accommodations and meals on the way there, and way back.
...and did I mention ICE for a week?
Definitely not cheap get aways, but also some of the best memories our family has