so i just finished adding holes to a wheel for lug nuts.  Did it with boolean. 

Made a cylinder, arrayed it, and booleaned into the wheel.

Then I spent some time snapping points together and getting rid of ngons and was able to grab the edge and sharpen it with bevel.

now...

Oshio suggested another way.  Find the area where the lug nut hole should be and position a flat disk.  Move points to match.  select polys inside, duplicate, extrude.

Ok, that works too, but you have to do it for each hole.  Sounds tedious.  Well, maybe.  I think the time it took me to make 5 of the disk / extrusions was way longer than making a boolean and arraying it, however, considering the cleanup time, it was about the same.

Here is an image of the boolean after I cleaned it up.  It is quads and tris, but no-ngons.