I was in the same boat you were in. I have run race spec coilovers on a street car and loved the handling but hated the harsh ride. When it came time to do the suspension in my 135i I wamted something that would be comfortable but would be able to handle the added power that the car now has. I was pretty set on going with the KW V1's and almost pulled the trigger, but then I came across the KW Street Comfort series Coilovers. They are basically designed to keep the luxury feel of the BMW but perform like a coilover. They are adjustable for both height and dampening (unlike the V1's) so you can set the car to any hieght you want and adjust the firmness with the turn of a screw. I also opted for the Vorshlag Camber Plates as well for more adjustability with camber, but they are not necessary.
I have had them in for a week and so far I really like them. The feel is slightly firmer then stock but I have them dialed in about 2/3's tward firm. I took my wife for a ride for the first time since the install and she did not notice a difference, and she always commented on how smooth the car felt. Under acceleration the car feels more planted and the handling is definitely more stable. They are more expensive then the V1's but if you want the quality I guess you have to pay. I hope this helps. I will be posting pics when I get a chance.
AFE Stage2 DCI,AR Design Catted DP's,N55 Mids,Maddad Whisper Exhaust,EMS 5" FMIC,ER Charge Pipe,Forge Diverter Valves,COBB AP,KW Street Comfort Coilovers,Vorschlag Camber Plates,19" TSW Londrina's,ContiContact 3's,Hartge Front Lip, Reiger Diffuser,BMW Performance CF Spoiler,CSR Eyebrows