That seems like a sound decision. The buffet has nice wood grain and, as you said, you can always paint it later.

The new piece is interesting! Anxious to hear what you have planned for it!

Rather than sanding the top you may want to go over the whole piece with "furniture refinisher" (I've used Formby's brand) and steel wool. I suspect that this would make the scratches on the top as well as any other flaws in the finish pretty much disappear. The stuff stinks so you'd want to do this outside and wear rubber gloves. Then apply a couple coats of varnish (tung oil is easy)and you're done...

I feel you on the internal paint debates! For what it's worth, I like the wood the way it is. Maybe you can just paint the wall behind it a more dramatic color or paint the frame of a picture/ mirror that will go above it.