Collision avoidance and lane departure are options I didn't get. I don't know how the former works with CC.
The Duramax 4 is not out yet, due later this year. From what I understand it will carry a hefty premium and come in the higher trim models. I was trying to keep costs and weight down so the ext-cab and 4cyl was the best choice for me. I'm pulling with a gas coach - for the DP's they can tow anything and weight is less of a consideration. The ext cab 4cyl is at least 500lbs lighter than the crew-cab long box with 6cyl. And costs at least four grand less.
I got the LT with the upgrades and would have liked to have the Z71 package but none were avail in 4WD unless I went completely loaded 4-door - they are getting near $40K. The z71 has upgraded shocks, fancy seats, a skid for the transfercase, and the emblem on the grill and box side.
I got locking rear diff, Bose and Nav, and the two LT packages that has all the lighting and convenience options - sticker $32,190. They now have all the luxuries we've come to expect of of modern luxury vehicles - auto headlamps, auto-up and down windows, beautiful 8" touch screen with or without nav, backup camera, heated seats option, auto-climate option, remote-start option, bumper corner-steps, bedliner options, cargo management options...and more. You can really load them up. Apparently much of the design team came from the Silverado line - they basically took all of their technologies from the big truck and stuffed into the smaller one. The reviews are all just raves, they are really nice.
The GMC Canyon is also very nice, several little upgrades to differentiate it from the Chevy, also adds at least a grand to the cost. I like the fenders on the GMC and the front end on the Chevy. And of course they build probly 10 chevys to one GMC.
The 6cyl is very smooth and a must if you intend to tow with it. But it adds over a hundred lbs and costs an additional $1250. After driving both, since I won't be towing heavy (up to 7000lbs for the 6cyl) the four cylinder works just fine, it is smooth and quiet unless you tromp on it - only then can you tell it's a four. The four gets just slightly better mileage.
The 6cyl is all the rage but it's a high-revving motor so the only place you see the extra power is at the top end. They feel very similar for around town and normal driving. My advice would be do drive both and decide for yourself. I was really torn, but in the end decided the lighter weight and lesser cost was to my advantage. The 6spd AT works REALLY well with it. Brakes and handling are also absolutely excellent, and it's so quiet it's hard to believe it's a real truck on a real frame with a real transfercase. And it gets really good mileage...almost as good as my the Subaru Crosstrek. Plus it's WAY nicer to drive than the little car.