After you leave Hiroshima/Miyajima, just go to Himeji jo - spend a couple of hours there and go on to Kyoto. It's nicer to spend the night in Kyoto than Himeji. That's what I did in April although I also spend 4 nights in Kyoto. Himeji is normally just a day trip. When you get off the shinkansen, just stick your bags in a locker at Himeji station (there are lots) walk to Himeji jo and spend 1.5 to 2 hours there. Then back to the station and on to Kyoto. If you want to save money, you could even take the night bus from Kyoto and arrive in Tokyo the next morning. Much cheaper than the shinkansen since your rail pass would have expired by then... and you save one night of accomodation costs.