Japan for 3 weeks

My fiancee and I will be in flying into Tokyo on March 9 and leaving on March 30. This would be sort of a honeymoon extension, but ideally the things we want to do see/do are the following in order of priority:

- Cherry Blossom viewing
-Ski/Snowboard
-Hot Springs
-Snow Monkeys
-Temples/Castles
-Nature/Outdoors (Mountains etc)
-Beach
...all the other touristy stuff

i'm in the process of planning an itinerary, since it might be too early for cherry blossoms we were thinking of starting south (so maybe Okinawan Islands?) then working our way up to chase the blossoms, or perhaps stay a couple of days at a ski resort first, can anyone help on the best way to go about this...? Please? it'd be greatly appreciated.

Your best chances of seeing cherry blossoms is during the last few days of your stay in late March in the Tokyo area.

Snow conditions detoriate quickly during March, so I recommend to go skiing as soon as you arrive. Hokkaido, Tohoku, Nagano and Niigata are some of the best areas for skiing:
http://www.japan-guide.com/e/e2262.html

Hot springs can be found across the country:
http://www.japan-guide.com/e/e2292_where.html

The "snow monkeys" can be observed in Nagano. The eralier the go, the higher the chance to see the snow monkeys actually in the snow:
http://www.japan-guide.com/e/e6025.html

thanks for the response, Uji!

I will def make sure to plan for the snow first in that case. As for the blossoms, if we were to head south after the snow, will we not be able to see any blooms in Okinawa or any that are starting to bloom as we head back up to Tokyo? I know that there might be some late March in Tokyo, but i thought that they start to blossom first in the south then slowly head northwards as the climate gets warmer?

So after the snow, perhaps we'll fly to Okinawa then fly to Kyushu and head northwards from there, ending in Tokyo. Does it make sense for us to plan that way? Any negatives?

As for the blossoms, if we were to head south after the snow, will we not be able to see any blooms in Okinawa or any that are starting to bloom as we head back up to Tokyo?

Cherry trees in Okinawa are a different kind than the ones in the rest of Japan. They bloom in January and February. March will likely be too late.

Tokyo is one of the first places in the rest of Japan (excluding Okinawa) to see cherry blossoms.

I know that there might be some late March in Tokyo, but i thought that they start to blossom first in the south then slowly head northwards as the climate gets warmer?

Tokyo is actually earlier than most other parts of Japan. It is explained here:
http://www.japan-guide.com/e/e2011_when.html

If you are interested in Temples or oveghtstay in temple in World Herigate site, I reccommend you to choose "KOYA SAN".
Of course Kyoto & Nara are famous place to visit temples but Koyasan is more quiet and calm place.

http://www.koyasan.or.jp/english/index.html