I am running a set of MarkMc's wheel spacers and my stock 17" wheels.
In the next year when I put on my next set of tires I was considering new rims as well, the 16"s just look better I think. But I don't really want to change the spacers to accommodate for a different wheel / bolt pattern. I can't seem to find the stock 16" wheel specifications any where, even tirerack and other sites I've poked around at all list only 17s for the trailblazer.