Thinking about a boat......

I have quite a bit of boat time in, and I can tell you that it is a blast if this is what you want to do.
I'm a scuba diver and I have spent a lot of time diving out at the Channel Islands, as well as Catalina.
The watersports were quite a bit of fun, like waterskiing, kids on the tubes, and fishing was ok till I moved to AZ. :-)
My boats were a little more functional for what I did with them.
My Bayrunner 16' aluminum deep hull was what I used in the ocean, and it had a 60 horse twin on it and I could run out to the islands in about 30 min.
Not very comfortable for playing, but held a ton of gear and could handle some pretty rough seas. (45 foot waves once) not recommended :-)

The favorite for fresh water was a trihull 18' fiberglass boat.
This one we used for fishing and playing, as it had trolling motor and live well, open bow and pulled skiers pretty well.

Both boats were fairly managable by one person, meaning one person could unload or load them on the trailer and they didn't use a lot of gas.
(20 gal or so per weekend)

One of my buddies on the other hand, had a 454 V8 V-drive that frikin flew, but he was at the marina getting gas all weekend. :-) (about 80 gallons over a holiday weekend)

Even with the boats I had it was a minimum $100 to do ANYTHING (even to fish at a local lake for the day)
Then there's trailer and boat registrations and insurance, tires, bearings and so on.