Thanks. What website would you reccomend for train timetables? Is it worth it to reserve a seat of any of the legs of my trip?

Two nights in Osaka, with one being spent in the city and the other in Himeji/Okayama. To reach both Himeji and Okayama, I take the Sanyo shinkansen.

Any thoughts on only doing one of them and doing Kobe (Kobe shinkansen or Sanyo)?