I'd say 1500-1600cc is a perfect 'all around' size. Plenty of power, but still pretty light and maneuverable. No problems exceeding any speed limit you'll find in the states, and have plenty more to give.
you ain't kidding there. I loved to toss my 1500 around those nice sweet corners in the farm fields.
...and that US 12 east to west in Idaho, stuff that dreams are made of there.