I have a 2012 GC Summit with 260,000 mostly highway miles. So far there have been 2 repairs to the air suspension system, both covered by MaxiCare. The most serious problem occurred while we were on vacation and involved an air bag that blew for no apparent reason. It sounded like a gunshot when it happened. The blown air bag occurred at about the 240,000 mile mark. The other, less serious (and expensive) air suspension repair, happened at maybe around 150,000 miles. I think it involved replacing some air lines that were leaking.
Getting parts and a dealership willing to do the repair on the blown air bag was a problem while on the road far from home. With one air bag blown, we pulled the fuse so the compressor wouldn't run, and the suspension settled down on the bump stops. By driving slow, however, we were able to complete our planned trip and drive the vehicle 2,200 miles to get home for the repair. I mention this, because I think it's important to know that a failed air suspension doesn't necessarily leave you stranded and at the mercy of who knows who or what out on the road.
Bottom line, I'm happy with air suspension and would get it again. The repairs were covered by MaxiCare as mentioned, and so far none of the other suspension parts like shocks, struts, ball joints, steering components, etc. have needed attention. I don't even think I've had an alignment.
Jim