I haven't been on the Tokaido Shinkansen, but I have been on the southern rail (from Kyoto to Fukuoka) on the Rail Pass. If you can afford it I highly recommend it. It's much cheaper than buying individually. One word of warning though...if you're not a smoker, request (or draw out if they don't understand) that you want a non-smoking car. If not, you'll end up like me and nearly choking to death with 75 smokers and their wafting odor. If I'm not mistaken, there are three types of shinkansen that run on the lines. One stops at all points (usually it's the old version). There's another version, the Hikari, that has less stops, but still quite a few. Lastly (and most preferable), there's Nozomi, which only stops at the very important cities. This is the only one I took because it's VERY nice and you really can feel and see the speed that it travels at. It's quite impressive. Don't forget to buy food at the station too, since it's quite limited onboard. You can't go wrong with the zarusoba. While on the trains, don't forget to pay attention to the conductors or the girls working on the train. They give a slight nod facing the passengers as a sign of courtesy. That definitely leaves you with a good impression of the Japanese. Have a great trip!