If you're looking at an S series, then you're looking for a value proposition and you want the best bang for your buck.
You should get either the twin ellipticals or the tri-toon with the regular 25" tubes, not the ESP. You can go for whichever one you can get the better deal on, but all things being equal, the twin-ellipticals will probably work better for you.
Get the underskinning so the water can't hit the underside of your deck, or more accurately, the cross members. If you want to squeeze your dollars for all their worth, you can do what some of the more creative tooners do. Buy some FRP at one of the big box hardware stores and screw it to your underside yourself. FRP is the pebble-skin sort of wall paneling you see in the restrooms of most public places. Lots of folks tuck the leading edge OVER the forward-most cross member, others just bring the leading edge of the panel flush with the front side of the cross member.
Now to the engine...
First off, if you're looking at pulling folks on a tube and having a few guests, you'll want the 24 foot boat. Two feet DO make a difference and it's only about a grand. Plus, on the 22 you can only get a 115 while on the 24 you can get a 150, and you're going to want the 150.
Second, take a good look at the Yamaha 150 Vmax 2-stroke. Modern two-strokes are not like the older ones, and two strokes do make some good power. Plus, it's like $1,000 less than the 4-strokes.
Finally, do NOT overlook the possibility of snagging yourself a left-over or even a used boat. You'd be surprised at how good a deal you can get that way.