I use raytracing quite a bit, so I generally have several bounces, even for test renders, unless I am just testing for light levels, or checking for poke-through, when I may switch to the default automatic settings.   The texture size I tend to use is  1280, but that depends on the render dimensions.   I use 0.2 in minimum displacement bounds, ecause that avoids rendering problems with irritating little black lines.   I start off with a maximum bucket size of 64, but often have to reduce that, to get a render to complete (or even to start, in some case).   I always use displacement maps in the manual setting and never use texture filtering.   Whether  I have ever actually achieved a "great" final render, however, is another question and one which may render all the above merely academic ;¬) .