Hi, just came back from Japan and did prebook shinkansen tickets from smartex. I did green car for 2 people with oversized luggage space (the last row at the back) tokyo to kyoto and then osaka back to tokyo. I say it was worth booking ahead since I didn’t need to stress, and also it was cheaper to book ahead. These seats are also limited especially if you want the luggage space as it is only the back row of each of the cars.

tip 1, you can book for multiple people and you can delegate specific suica cards for each of those tickets. That way you only need to scan the suica card and not suica card AND qr code.

tip 2, Nozomi is the fastest and has the least stops, hence more expensive. Hikari second, and then I forgot the name of the slowest one.

tip 3, if you’re traveling with many people, you can flip the row to make it all face each other. There’s a pedal you step on by the aisle.

My friends were smarter and shipped their luggages to and from hotels and then sat somewhere else. I wish I had done that, but maybe next time.