I think I'm inclined to agree with sticking with 4 lug. With Honda, VW, some BMW, Mazda (especially Miatas) and many others involved in the slammed / stance / whatever trend that's going on right now, you will probably have pretty good luck finding some of these custom wheel sizes and offsets that you desire. While 5x4.5" (5x113.4) is also popular, I don't think the selection is out there as much.
^ Coming from a guy who has 3 cars with 4x100 pattern and one with 5x114.3
Depends on wheel size IMO. 16" and under have a ton more 4x100 selection, but 17" and up have a lot more 5x114.3, so it really depends on what wheel diameter you are looking for.