Tru-Oil over walnut and maple. I'd call this "semi-gloss", but if you really want satin, it can easily be knocked back with a grey or white scotchbrite. It's not as durable as wipe-on poly, but I think maybe a little harder drying than Watco.
I'm also very happy with Tru-Oil on my walnut/maple Carvin. I've used Tung Oil on walnut before as well, including on this same bass, but I think the Tru-Oil looks at least as good, if not better, and provides much better protection (although agreed that it is not remotely at the level of protection of poly).