I went with the Koni FSD/Eibach pro kit springs combo with 19" Breyton rims. http://www.e90post.com/forums/showthread.php?t=310984
I think the drop in ride height with 19" wheels is just right. Also great improvement in ride quality.
2008 Monaco Blue/Tan interior 335i sedan. Mods: AFE intake w/ scoops, AFE Exhaust, ER FMIC, Koni FSD/Eibcach Pro-Kit, Breyton Race GTS wheels w/ Continental ExtremeContact DW tires, Cusco OS strut bar. BavAuto Black/Beige seat covers w/ black floor mats, M3 rep trunk lip, eBay front splitters.