Renting is always the best place to start.
Camp the first night in your driveway.
(Those are the standard answers for those unfamiliar.)
As you are not already RV people, take the time to go and look at both. Yes, smaller is easier to handle (says the guy that now has a 23'A), and even a few feet can make a difference. But, if you can't sit down in it with the kids (you have to bring them on this mission) and imagine being stuck in it for a whole day (weather can do that) and surviving, get larger.
If you don't do this, you may be scared off the best mode of excursion travel available.
If you are going to go traveling, things are a little (but not much) than if you are going to a cramp ground.
Matt - (my "14yo" now has a 12yo)