Re: Low end theory....
For 8 people (kinda' squished) or 6 people (fairly comfortable) a 18 or 20 bow rider will do. You could go bigger, but somewhere in the 24' range, I think launching, retrieving and maneuvering in close are harder learned. Not impossible though. People do it all the time. I have a family of 5 - usually take 2 dogs - and sometimes take full capacity (8 people) out on my 18. It's tight, but not too bad.
I typically suggest out boards to newbies (I think they're easier to learn), but you'll find mostly I/O's out on the market over 18 feet.
You might look at deck boats, but they're hard to come by. There are some center console or walk-around types that might do as well, but I think you'll be looking for something slightly more suited to dragging tubes and skiers around. Really, it might do to visit a couple of dealers and crawl around on things and see how you fit in them and like the amenities. With your budget the used market will be pretty wide open.
Good luck - shopping is half the fun.
