I've not used anything like a vinyl mat, but do have a 5x7 area rug in my bathroom that functions as a bath mat. It's near enough to the shower and tub to step out onto, and is large enough that it doesn't slip or slide around. It's polypropylene and easy to just vacuum routinely.

I'd be concerned about moisture getting under the vinyl mat or water damage in general. With a bath rug, just toss in into the wash if it gets too wet for whatever reason. Maybe a vinyl mat in front of the vanity, but to step out of the shower or tub, I wouldn't.

My bath mat is only on the floor when I get out of the shower. The rest of the time it is folded in half and stored on the long bar outside of one of my frameless shower doors. I agree bath mats do not look all that great when used as area rugs.

I use a slatted teak mat. Stand it in the shower after drying off.