The selection of the groups is pretty much up to me and the manager of the potential group. At the end of the year, I will rotate into a final placement and work there for the duration. I'm currently in my first rotation, which is with a group of people looking at compiler technologies to take advantage of some new architecture ideas Intel is considering for the next generation of processors. I like where I am now, and I'm learning gobs. If I do go back to grad school after a few years, I'll be a much stronger student.
Life is good.
My biggest mistake in grad school was in expecting it to be like college. In college, classes are important and are the most important thing academically. In grad school, on the other hand, I found classes to be of secondary importance. What is paramount, at least for the PhD, is research. Unfortunately, I did not come to this conclusion until very late in my grad school career, after I had spent much of my energy taking grad courses that were of little importance to me.