Like the others have said, your sign looks amazing!! As far as the multiple stain colors go, have you considered using a gilded wax? Most of them are metallic colored (gold, silver, bronze, etc.). I used some years ago on some picture frames that my dad and I made. Turns out well, and you don't have to worry about drips or the color bleeding into other areas.
DecoArt is the maker of such a product, they call it Metallic Lustre Wax and is available at Home Depot and probably many other places as well.