Pretty traditional to have wood floors in a yacht. It's only money that has attacked that tradition, though there may be folks who actually like vinyl, plastic or carpet flooring.
Unvarnished Teak with raised Holly strips was the old European fishing boat interior flooring; you could clump around in your wet boots and not slip so readily. Plenty of older boats happily made do with laid plank decks.
Yachties took a liking to the Teak, but with flush Holly strips, and varnish. It's such a beloved classic look that there are plenty of veneered plywood and plastic products made to emulate that look.
There are technical and maintenance issues to be handled. Sure, it's your boat's interior but there's plenty of sunlight and tracked-in water, let alone galley spills, leaks from ports, etc., to make warping and finishes a tougher problem than in your home. Depending upon your boat's layout, some of this floor will be over the engine room, so noise and heat, as well as drying are to be handled as well. Some of this flooring will be over bilges which may well be damp.
Now some specifics (retired classical architect here...): Your structural floor is probably plywood; presuming you can get it clean and smooth (from old glue, etc., adding wood flooring should be no problem. It would add weight, thermal and sound insulation, and may well meet your taste.
1, No need, and probably no desire, for a residential-type T&G wood strip flooring, but nothing technically wrong with it, either. The separate strips will handle expansion and contraction and an exterior urethane finish would do.
2, A glued strip floor (including the classic Teak and Holly) or parquet would be fine as well. As is for #1, the strips will handle...
3, A plywood sheet flooring would work, and best, I think, if glued. Joints would have to be considered for looks (often dropped into areas separated by the fiberglass structural grid in sailboats) and potential for chipping. The finish would have to be suitable for the use; you might get one refinishing out of it.
4, A plywood flooring product in small-ish pieces, usually with T&G edges would work. Typically, these are glued down, but many are intended to be 'floated' or adhered with double-stick tape. I think that either the floated or taped installations would be less suitable on a boat (I've seen this stuff buckled up in the middle of floors. I've seen this stuff where the individual 'planks' had cupped.) You'd have to be sure that these floors had an adequate finish for the marine service as the veneers are thin and there's no refinishing 'em. Many of these products have beveled or eased edges to protect the veneer edges; it's a look many folks don't mind. Many of these products are faced in smaller pieces of veneer to mask the 24" x 8" common size; it's a look that many folks don't mind.
5, A prefinished solid wood floor is another alternative. Typically, they are T&G, the same thickness or less than ordinary strip flooring, and have eased/beveled edges. I think many are finished top and bottom. Some may be sold with 'heavy duty' finishes, but the UV resistance would have to be assured. You can refinish 'em but I'd wonder about the appearance of the old finish at the eased/beveled edges.
I liked the solid Teak strip flooring I epoxied down to the fiberglass sole in our old sailboat. Epoxy-coated and urethaned. (Current owner likes it, too.)
I like the solid Teak and Maple flooring, made up into 6" wide planks and screwed down to sole beams in our 44-year old Dutch-built sailboat. Original finish looks pretty good.
I like the solid Teak and Holly strip flooring glued down to Fir plywood in our '84 Taiwanese trawler. Original finish looks pretty good, some areas repaired by a PO.