Go for the big rig. We just jumped from a 30' to a 39' and have some concerns getting into some of the older campgrounds in the northeast. we discussed this at great length and decided that if we can't get into the CGs that we like, we would find different CGs that we'll learn to love.
More the concern is ground clearence issues than lengh issues. having a longer wheel base and a lower frame/chassis height then our previous MH I worry that I'll bottom out and get the chassis "beached on a hump/ knoll on some of the back roads in new england and my drivway. Go it I say. Friday the 5th is when we take delivery of ours, we'll repor back regarding manuverabilty