[samokan]

you will be here in time for Sakura?

Then I suggest not to miss Kyoto: Philosophers Path, Botanical Garden, Arashiyama, and Yasaka Shrine , among the places where you can watch some great sakura. Usually in Yasaka they have light-up there until around wee hours in the morning. The big sakura ( forget the name ) is being lighted, its really really beautiful so don't forget the tripod.
Arashiyama, don't miss out the place its really amazing there on spring.

If you are going to Osaka Castle, try to pass by Sakuranomiya also. Just outside the station is the river and both side of it are all Sakura trees. The place is full of people till wee hours in the morning drinking under the sakura tree.