Taylor did a run of their "acoustic" series in all-mahogany last year if I remember correctly. They looked really nice, although I can't say I love the red stain Taylor often uses on their mahogany. I prefer a traditional brown coloring or even just the more gold natural color.
If you're looking for all-mahogany and not set on a Taylor, there are two awesome options above and below the price range you'd be looking at for a BTO or limited.
First is the Martin 15M series -- which I think is the best bang-for-the buck out there right now. I've heard nothing but good reviews and the couple I've played were awesome. They really nail that vintage look and sound and will do it for less than half the price of a Taylor.
Or, for a bit more cash, the Santa Cruz 1929 series (essentially a boutique homage to Martin's old 15/17 models) looks absolutely stunning.
That said, don't rule out a Taylor -- I bet you could make a stunning mahogany BTO with shaded edgebursts.