Some boat basics.
"Boats are holes in the water that you pour money into." is an old adage that usually rings fairly true.
Boats normally do not retain value immediately after initial purchase, but tend to find a solid price a couple of years out. So, the best purchase for my money is a boat that is pre-owned, by someone that clearly cared about taking good care of it.
For all around fun, riding on the water, the newer two-pump jetboats that SeaDoo and Yamaha make are just a total blast! If you wanna sit and party in your boat, they are not the way to go. If you love water skiing, they'll work, but again, they are not the way to go.
For the most passengers per boat foot, pontoon boats can handle the most people, but are the least versatile. Open bow boats (like the Mariah we have) are the most versatile, but by nature, aren't great at anything. We can ski/ wakeboard/tube/tie off however.
Boats burn a lot of gas, have a budget to enjoy the boat even after you paid for it.
Loans on boats - nope, bad idea. You'll be paying far longer than the boat is worth the payoff value on the note. And making payments in the winter on a boat sucks as well.
Make sure to get good storage.
Make sure to use a boat cover.
Make sure to winterize.
Those are the basics, hope that helps.