The size of the lift is very specific to your wants and needs, the terrain you will travel and your vehicle. I had an 03 Excursion with a five inch lift and 35 inch tires. So theoritically it was 8 inch taller than stock which sounds like a lot, but for the length and width of the vehicle it really wasn't. I wanted the vehicle to be comfortable on any terrain but still have the clearance for almost any trail (or any trail that was wide enough). I can tell you that given the size of a suburban and the stock ground clearance, I would be very surprised if you ever encounter any areas that a 4" lift and 35"s would not get you out of unless you go rock crawling where the rocks are 15 inches or bigger.