Bib shirts are popular because they look good, are very historically correct and besides that John Wayne wore them a lot.
If you make your own shirts, the bibs on a bib shirt are one of the easiest part of a pattern to modify to fit your own taste. In fact and 4 button placket shirt with out gathered sleeves or front piece can be made as a bib shirt.
The easiest way to do this is to take a large piece of paper and fold it in half. I usually make the rest of the shirt first so I can use it to see how it looks and fits. You then cut the paper with your sissiors away from the fold, kind of like when you made Valintine hearts for Mom to hang on the ice box. Unfold the paper and lay it out on the front of the shirt, does it look like what you had in mind?
If so cut two pieces out of the material, interface it and sew your seam, leaving enough room to turn it inside out. Blind stitch the rest of the seam and sew a seam all the way around the bib about 3/8-5/8 in and a second one about an inch in. Put your button holes where desired inside the seams and sew the buttons on the shirt. With out the thicker material of the placket it is a good idea toe sew the outside buttons to a small buttons on the inside. This will keep the main button from pulling through the 1 layer of material.
I make a lot of heavy quilts using flannel shirts and save the buttons from them to use for this, but any cheap 3/8-1/2 button will work fine for this.