I can see where Stick's method of using two hole saws with the smaller one being a guide for the larger one will work well for some situations. For small holes that need to be opened up and kept on the same center, I use a step drill bit to open the surface to the the size needed and then use a straight drill bit of that size to clean out the smaller diameter steps, if the piece being drilled is too thick for one step of the bit to cut completely through.
For drilling larger holes I have Forstner bits in 1/8" steps from 1/4" up to 3 1/2". By using a scrap piece already drilled to the diameter needed and clamped in place to use as a guide for the desired size Forstner bit, I can drill out a hole to the new diameter, up to 3 1/2". Beyond that I resort to a router, 1/4" bit, and usually my CRB7 jig. I can go to over 4' diameter using that.
Many ways to get this done.
Central North Carolina