Many thanks. Don't let the rigging of the Sultana scare you. That ship has about a tenth as much of it as either the Hancock or the Bounty - and you're working on a scale that's twice as large. That kit is just about the best one I can think of for introducing rigging.
The figures on the Bounty and Hancock models are came from plastic kits - sometimes with fairly extensive modifications. The following oddly-assorted kits have figurest that are the right size:
Revell - Bounty, Santa Maria, and harbor tug Long Beach. (The Continental Marine on the Hancock's forecastle started out as the soldier with the helmet and breastplate in the Santa Maria, and the captain of the tugboat is standing on the footrope under the spritsail yard.)
Airfix - Endeavour.
Aurora (ex-ITC) - Sea Witch. (The figures in that kit are pretty obviously pirated from the aforementioned Revell kits, sometimes with their poses altered a little.)
The figures on the Phantom are HO railroad people from the excellent range made by Preiser, of Germany. Preiser figures come in two forms: small sets (five to eight people each), prepainted (not very well, but quite expensive), and large sets, unpainted (terrific bargains). These particular guys came from a big box of nineteenth-century railroad people. (As a matter of fact the figurehead of the Hancock is also a Preiser figure. On the real ship he was larger than life size. By pure coincidence, putting the model on 3/32"=1' made an HO person just the right size. He's got a new hat, new legs, and new jacket, from sheet styrene.) The cat looking down the after hatch of the Phantom is from a set of cats and dogs made by Woodland Scenics, painted in the markings of my landlord, Willie II. The checkerboard is also from a Woodland Scenics set; the checkers themselves are slices of plastic rod.
HO scale is1/87, which obviously is a little bigger than the Phantom's 1/96. The people who sculpted the masters for HO figure sets, however, seem to have different ideas about how tall adult human beings are. In a given Preiser box some of the people are going to be conspicuously too big; others are right about six feet tall. If you're looking for a crew for a 1/96-scale ship, it's worth looking through the stock in the railroad department of a good hobby shop. Quite a few companies make figures that can be pressed into service.
It should also be remembered that the big Revell sailing ship kits, the Cutty Sark, Constitution, and Kearsarge (and their clones), contain beautifully-sculpted figures on 1/96 scale. So does the company's so-called "Spanish Galleon," which otherwise doesn't deserve to be labeled a scale model. So does the little Revell Golden Hind.
I've never wrestled with the problem of finding people on the Sultana's scale, 3/16"=1' (or 1/64). Such individuals should be about 1 1/8" tall (or a little shorter). I don't know of any commercially-available figures that meet that description - though I think Model Expo may offer some cast metal ones.
It might be worth looking at some of the many sets wargamers' figures on 1/72 scale. A six-foot person on 1/72 scale would be 1" tall; he or she would be 5'4" on the Sultana's scale. That's not an unreasonable height - especially in the eighteenth century. (We've all heard that people were shorter in those days. The difference is often exaggerated in the popular imagination, but there's some truth to it. And some individuals are still 5'4" tall. I happen to be one of them, as a matter of fact.) Most of the 1/72 sets I've seen are molded in soft plastic, which makes it tough for paint to stick to them when they're handled. But on a model in a glass or plexiglas case that's not a problem.
I agree completely that figures add a great deal to a ship model. One of my heroes is Harold Hahn, who carves his own exquisite figures out of wood. His "Colonial Shipyard" diorama in the Mariners' Museum, where I used to work, is a masterpiece - and includes a wonderful model of the Sultana.