Definitely go with the staggered wheel setup. It looks so awesomely mean in the rear!

See this thread for pics of mine (I've since sold it!) with a set of the staggered OEM 214s with the regular flares. It looks fine with them and you can definitely skip the extended flares if you prefer (and I hear that they've gotten expensive). I did end up adding the flares shortly after these pics were taken, but it's all personal preference I suppose...

http://www.xoutpost.com/bmw-sav-foru...hire-214s.html

__________________
2009 E90 M3 M-DCT | Alpine White/Black/Carbon

SOLD: 2008 X5 3.0si | Black Sapphire/Black Perforated/Burl Walnut | Premium | Sport | Cold Weather | Premium Sound | Active Ventilated Seats | Auto Tailgate | Comfort Access | Running Boards | Heated Rear Seats | PDC | OEM 20" Style 214s | Titanium Kidney Grilles | Tint 20% Rear/35% Front | GP Thunder 7500K Halos | Xenesis Fogs