Randy,
My Bo-Jest handles 2-3' waves safely, but not comfortably. I don't know of a 20' boat that is comfortable in those conditions (at least not for us OLD GUYS

)
We've put over 1000 miles on the boat so far, mostly in the rivers, but a couple of hundred miles was in Mobile Bay and the ICW in Alabama and Florida. Wake from other boats was never a problem as long as we turned and met the wake head on.
Almost all of our travels have been with me, the wife, one grandchild, and a small dog. Our longest cruise so far was 7 days, and although the space is tight, we were comfortable. I'm working now to put some storage space in the boat to help corral the junk that seems to accumulate on a long trip (binoculars, log book, cell phones, PFDs, etc.).
I understand that a couple of guys did the great loop on jet skis once, so doing it in a 20' boat would probably be possible, but I would think you'd have to really be flexible on your schedule and let the weather dictate your travel much more than if you were in a bigger boat.
Whatever you decide, you'll make some great memories with your grand child. We've had all 5 of ours on the boat, and they love it!