I've sat in a couple Silverados, for a truck they seemed fine, likewise for the Suburban (same dash as higher line Silverados). I had an F150 rental last year, the dash was a mess of too many wierd elements, too many cutlines and very cheap plastics.
Personally, I like the "basic" dash layout offered in the W/T, SL/LS, and SLE/LT model interiors of the Sierra/Silverado (not that the luxury dash [sLT/LTZ] isn't nice, but to me it's too car-like for a truck). But as Oldsmoboi pointed out, they share in parts with models no longer produced by GM and the new interiors of GMs vehicles have gone far above and beyond what any GM interior has offered to the consumer, so why should the cash-cow pickups and SUVs suffer still? I also agree with your sentiment on the Ford F-Series interiors. I've driven one 2011 F-150 (last November), the model below the XLT but not the basic work truck, and sat in F-150s of differing models at both the Philadelphia and New York Auto Shows this year and feel as if Ford is trying to be 'techy' & 'busy' with their dash design. I did not like the feel of the $37k XLT or the higher priced models dash/interior and thought that GM should not be the only one suffering from critics reviews of full-size truck interiors.