I just got off the phone with the local rack shop, they said Thule still doesn't have a fit for the new yukon/tahoe/suburban which came out around this time LAST YEAR! I wouldn't hold my breath for thule to release a compatible fit anytime soon for our GCL's.
REI has all the right Yakima towers, landing pads and crossbars in stock but the total is $643. Much more expensive than the Plymouth-roadrunner-wing height OEM ebay special at $275. The rack shop guy said the Yakima towers sit up much higher than the thule's also. Shoot.