Trying my luck here.. going to Japan in a couple weeks, solo traveling with an unplanned itinerary.. Anyone have recommendations for attractions?

if you are in Tokyo, check out the Tokyo world cities app from tripadvisor, you can use it on your phone without data, because it downloads directly to your phone and it only uses the GPS. And it is AWESOME. It has a compass built in to point you to your place of interest with remaining distance, recommended itineraries, great maps, and rates all the usually tripadvisor stuff by neighborhood.

Tokyo Skytree is expensive but worth it on a clear day

I just came back from Tokyo, Shinjuku is a nice place for shopping.

Tokyo ideas: Shibuya for the crazy crosswalk and the shopping and nightlife in the adjacent alleyways, Harujuku on a Sunday for the fun youth culture and more shopping (Also Yoyogi park is in the area), Tsukiji Fish Market early in the morning to catch the tuna auction (Also super fresh delicious sushi for breakfast)!

Dengue carrying mosquitoes have been found recently in Yoyogi park so make sure you wear bug spray.

Osaka and the Momofuko Ando Instant Ramen Museum. So awesome. The Aquarium there is great too! And the Dotonburi district will keep you fed and watered and entertained for days!

Shinsaibashi in Osaka for shopping

I'd suggest going to Gifu prefecture and staying over at an onsen resort during the winter.

http://www.jnto.go.jp/.../loc.../regional/tokyo/asakusa.html

just warn you that international bank cards can only be used at 7-11's and post offices. http://www.japan-guide.com/e/e2208.html

I had 3 days in Tokyo earlier this year and since two of them were pouring rain, I crammed everything into one day:
http://www.findingtodd.com/.../day-102-last-day-cram...

Should definitely go to Hiroshima too, very moving experience

Oh, and visit Shinjuku Gyoen - it's the national park amoungst all the buildings in Tokyo - picture Stanley Park x 10... so beautiful

If you visit the shrines or temples, go on a Sunday and you may see a wedding procession or two.
Heads up for ATMs - I bank with TD, my Bmo MasterCard and TD visa and debit cards did not work at the 7Banks; worked fine at the JP bank in the post office. My mother in laws CIBC debit worked at the 7Banks though. So just something to be cognizant of if one machine doesn't work.
Many noodle houses you order and pay via a "vending machine" and give the receipt to server. They do have English menus available if you ask.
Meiji Shrine is near Harujuku, also nice to walk through the park. Sensoji temple very busy with tourists but still cool to see if you're into history. 5¥ coin (usu unmarked and hole in the center, 50¥ coin is marked with '50') is considered luckiest for the boxes at temples and shrines.
If you're big on electronics Akihabara has tons! As well as the maid cafes. Super Potato in Akib has old school (and new) Nintendo stuff.
If you're arriving at Narita the NEX train had a special for 1500¥ one way into Tokyo, great price. Return via same train was about 3750¥.
I didn't get to check it out but the government building offices are free and you can go up at night to check out the views. Govt building area is in Shinjuku.
Vending machines for drinks are pretty much same price as the convenience stores.
The fish market, didn't make it but recommendations from many sites tell you to get there early, before market opens 430/5am. Note that the trains don't start until 5am. Something to consider if you're planning a trip there.
If you go to the Imperial palace you need to pre-book online with the Imperial office. You can't just show up, you'll be denied at the gate. Have to say due to when the palace was built, it felt underwhelming. The east gardens next to the palace were nice to walk through and do not require reservations.