Four Lambdas seems a bit much. I own an Acadia and love it, but can't imagine why they would sell the Buick version on the same lot. If they were smart, they should have fancied up the Enclave a bit more and sold it as a Cadillac and dumped the SRX, which does not seem to be doing too well.
Shopping for a Saturn these days is not really any different from any other GM brand....I don't think they are sticking to the "no haggle" pricing strategy any more. They should combine the Saturn and Chevy dealerships and slim down the product line on each rather than sell multiple versions of the same car (Outlook/Traverse, Ion/Cobalt, etc).
Its going to be interesting how they differentiate the Chevy from the GMC....I would consider them the most "like" brands. Subjectively, IMHO, the Acadia is the best looking of the Lambdas with the Outlook as a close second...I think its selling the best as well - its hard to imagine they would remove it from the GMC line-up. If anything, they should put a deisel or a V8 in only the GMC...fits better with the "professional grade" image...I would imagine that they could sell more if at least one version had some adequate towing capacity (4500 lbs is not bad, but I would imagine limiting for some).