The two Fleetwoods are essentially identical - just very minor differences in trim between the two brand names. The Minnie Winie, of course, is a Winebago product rather than Fleetwood so there are more visible differences, but nothing that is earth shaking. Winnebago uses a slightly longer wheelbase in their 31 footer (216 inches vs 214) and some folks like the Winnebago-style sofas, storage bays (the "Stor-more" system), etc. but that's mostlya matter of preference.
To get a good deal you just have to hang tough. Make a low offer, about 20-25% under MSRP, and stick with it. Don't be afraid to walk out of the dealership - they will call back if they don't make a beter offer on the spot. Your feet are your best bargaining tool - go elsewhere to find a deal.