Where to go in Japan during Spring?

Hi all

I am intending to visit Japan early April next yr for ~1-2 weeks to catch the cherry blossom season.
I have been to a couple of areas before (Tokyo, Osaka, Kyoto, Fukuoka, Hokkaido, Kawaguchiko, Hamamastu) and would like to visit new areas.

I am likely to be travelling solo, hence accessible transport (bus,metro) would be preferred. Not quite a big-cities person so nature would be good.

There is a whole list of locations here on japan guide but I'd like to hear from your opinions. Would Chuubu region be recommended since i'll probably be flying in from narita?

The Chūbu region looks like a good choice - lots to see and do, and plenty of natural attractions which is what you're after. I've visited several places in that area but haven't explored it thoroughly, so I'll leave it to more seasoned travellers to offer detailed suggestions.

The Chūbu page of Japan-Guide is a good place to start planning, though you've probably already seen it:

http://www.japan-guide.com/list/e1104.html

I'd also like to throw in a good word or two for the Chūgoku region, though it'll involve a long journey if you're flying in via Narita. Of course, if you can tweak your itinerary to fly in via a closer major airport (such as Kansai), or if you're travelling with a rail pass, then access becomes less of an issue.

The Chūgoku area has plenty of major attractions (Hiroshima, etc.) as well as a lot of less well-known gems. There's Tsuyama, for example - a great place for hanami if you're timing's right...

http://withinstrikingdistance.wordpress.com/2013/04/18/field-report-ts...

...and Takahashi, which is a nice spot for soaking up an old-town atmosphere.

http://withinstrikingdistance.wordpress.com/2013/04/07/field-report-ta...

More about the region here:

http://www.japan-guide.com/list/e1106.html

I visited Miyajima when it was Hanami time and it was so beautiful, really. Loads of tourist but still managable.

Hiroshima was super scenic too. :)

I love Matsumoto,Tsumago,Magome.
Takayama,Toyama,Kanazawa etc..
http://welcome.city.matsumoto.nagano.jp/
http://www.town.nagiso.nagano.jp/foreign/en/index.html
http://japanpockettravelguide.weebly.com/chubu-area.html
And more Takato Sakura was very beaytiful!
There are many cherry blossom area in Chubu.
http://takato-inacity.jp/h26/

Thank you all for the suggestions, I'll start narrowing down from your suggestions

Do throw more ideas at me :)

There are famous places that are all over Japan. The problem is that there are huge crowds going to see them too. Someplace that is nice without the crowds is a much better experience.
Since you have time and are willing to travel, there are a number of possibilities.
One place that was very delightful was actually Iwakuni - with the bridge it was very beautiful, and a visit up to the castle was a very good experience:
https://www.youtube.com/watch?v=0COOZXi66mM
Another gem with almost no people at all was in Handayama in Okayama City. Most rush over to Korakuen, which is also worth a visit, but overlook this very beautiful botanical garden:
https://www.youtube.com/watch?v=JGQ8o7k9GbA
Two other overlooked places are Maizuru Koen and Nishi Koen in Fukuoka. Some people, but not overwhelming:
https://www.youtube.com/watch?v=968CH00PboY
https://www.youtube.com/watch?v=y-pJPZjNVx0
Lastly one other beautiful place was a day hike to Konpirasan in Kotogawa, Shikoku. The sakura there were something wonderful, and in addition to the nice hike up the mountain to the nice shrine and splendid mountaintop view:
https://www.youtube.com/watch?v=ley9rVIewoQ