So I'm still perusing craigslist every night to see what's new that pops up for sale. Man, I had no idea just how many different brands there are and how many of them were manufactured right here in So Cal, although I guess the latter would make sense.

So more questions: Is anyone (Nixonnow and/or crewchief22  ) willing to offer a brief explanation of the various hull types I've been seeing? Flat bottom is flat bottom, but what makes a river bottom a river bottom and where do semi-V and V-bottoms fit in? Are there typical speed and handling traits that go along with each hull type, or are these traits noticeably different among various brands as well as hull types?

Notice that I didn't ask you which one is best...

http://www.boatingbasicsonline.com/content/general/3_5.php

I'll give it a shot. Like you said the flat bottom well is a flat bottom. They are rough riders in chop. Mostly used in vdrives.
The v hull is what you will see in most jet boats. Some shallow v, some have a deeper v. The shallow v is the faster of the two. Less drag in the water. Depending on the lay-up of the hull (heavy or light) the shallow v would be a rougher ride. Not always true though. My 19 hallett bubbledeck is a shallow v but built with a heavy lay-up so it rides pretty damn smooth even in chop.
The deeper v hulls will be a smoother ride because the v being so deep it cut through any type of water condition with ease. But it will suffer in speed because of the deep v (more drag in the water).
There isn't really a "best" one. They all have their own good points and bad points.
Hope I answered at least some of your questions lol. 

Beer! He said

Sent from my ADR6400L using Tapatalk 2

There are also Gullwings and Tunnel hulls.

http://www.socaljetboats.com/boat-showcase/new-rouse-19'-gullwing-hull/msg181778/#msg181778
The Gullwings are similar to the old tri-hull design but much faster hulls.

http://www.socaljetboats.com/projects/southwind-dragster-buildmaiden-voyage-fathers-day/msg100969/#msg100969
The Tunnel hulls use air-entrapment to help gain lift.

Both can be great river/lake boats but might be harder to find with the seating you're looking for.