Nagoya is a rather dull, workaday city. Fukuoka - and elsewhere on Kyushu - is a fine destination but rather a long haul. If you were to go there, I'd suggest stealing a day or two from other locales and spending the extra down there. From Fukuoka, it is a relatively easy stretch to Nagasaki and Kumamoto. Perhaps a trip up Mt. Aso to see an active volcano might interest you.