Suzuki used to make a 450 or 500 GS- F a few years back. It had the same rake and suspension as the GSX-R models, same basic look, but no sport-bike fairing, and a respectable second seat. Not sure if it's still made, but I know it was much more tame when compared to the GSX-R.
Have you given any thought to the 'Enduro' look bikes? Little bit more upright, V-twin motor for predictable power delivery and anywhere from 250cc to 600cc... jus' me 2 cents.
Good Luck.
-M.