A day trip from Fukuoka by train

I would like to take a day trip from fukuoka. is nagasaki doable in a day? is there anything in the kitakushu area? any other ideas?

Thank you!

Access
http://www.japan-guide.com/list/e1108.html
http://www.at-nagasaki.jp/foreign/english/about/access/
http://wikitravel.org/en/Nagasaki
Hakata[博多]city is biggest of Fukuoka PF/Kyusyu .

about Nagasaki
http://www.japan-guide.com/e/e2162.html
http://www.at-nagasaki.jp/foreign/english/spot/
http://www.at-nagasaki.jp/foreign/english/pamph/

http://www.flickr.com/search/?q=nagasaki&z=m

Yes, Nagasaki is doable as a day trip.
As for Kitakyushu, this really depends on what you are looking to do or see. I suggest you do a Google search and read up on the area.

Nagasaki has a lot to offer and deserves more than just a day trip from Fukuoka. There are other worthwhile destinations which are closer to Fukuoka that can be done as day trips.

Dazaifu and Yanagawa can be combined as a day trip from Fukuoka.
http://hu2.heteml.jp/dazaifu/
http://www.japan-guide.com/e/e4850.html
http://www.yanagawa-net.com/
http://www.kawakudari.com/

Kokura is worth a brief visit and nearby Space World is fun if there are children in the group.
http://www.kid.ne.jp/kokurajou/html/index.html
http://www2.kid.ne.jp/teien/
http://www.riverwalk.co.jp/lang/english/index.html
http://www.spaceworld.co.jp/

Mojiko is another worthwhile consideration. Most of the town's sights are within walking distance from the JR station. A short bus ride will bring you to Shimonoseki-Mojiko Tunnel where you can walk back to Honshu.
http://www.retro-mojiko.jp/
http://www.harusio.com/natukasi/natukasi_ooazamoji_3.htm

Starting March 12, Kyushu shinkansen is operational all the way to Kagoshima. The fastest Mizuho takes only ~1hr.20min. so just about anywhere is possible in Kyushu for a day trip from Hakata.
http://kyushushinkansen.com/cms/wp-content/uploads/2010/12/jikokuhyo.p...
Mizuho=Like Nozomi JRPass not usable.
Sakura, Tsubame are like Hikari/Kodama & JRPass valid.

I think the trip to mojiko looks interesting. I was thinking the same thing about nagasaki that it would be best to go for a weekend rather than just a day.
There are no children just a group of young adults going.

Just looking for some interesting things to see without spending all day on the train. an hour is great.

Thank you for all your help! if you have any more ideas it would be great.