My family just returned from a one week vacation (March 19 - March 26).  We stayed in Osaka and visited Kyoto, Nara and Hiroshima.  We had a great time, and had no problems related to the recent earthquake and tsunami.  There is no need to cancel your trip to those areas.  Everyone was very friendly and helpful to us.  The plum trees were just starting to blossom, in addition to a few cherry trees.  The tourists spots were not very crowded and we did not see many other foreigners.  Other than a couple of collection boxes for the relief effort, the Kansai area was not at all affected.  We had the impression people were happy to have our business.  My teenagers especially loved the deer in Nara and the monkeys at the Arashiyama Monkey Park in Kyoto.