I ran and operated a wheel and tire store for the last 7 Yrs. Spacers can cause major headaches...
Designo,You have a nice stable of cars, So I know $ isnt an issue. Alot of the Spacers Designed today, EIBACH, H&R, or the TCS sportline are all Race oriented. Though hub centric, Industry leaders will tell you spacers arent for daily driver use. (I'm not saying their not structually rigid enough, use em everyday if you like) but dont be suprised if you have different windows of vibration with all the spacers you use.
IF you want your brand new flagship, Luxury Sedan to ride like a dream, Dont cut any corners, and get some wheels with the correct offset, to fit your visual desires.
+35mm or such. You might want something closer to +30 in the rear.
Good luck. :D