Susan, remember that the default "lens radius" setting (0,10) is almost always way too high and blurs the image way too much. My first pic using DOF used the default setting and the background was really a mess, even at 64rpp. So, my advice is to use a radius from 0,01 to 0,05/0,06 (this latter, IMO, being the maximum to avoid excess blurring). For the graininess, it strongly depends on what light and materials are you using. Most of the times, I find 36rpp enough, but sometimes you have to go for 64rpp (specially if there are shiny mats involved). I never find of much use crankin up the rpp above 64. Hope this helps. Stefano