train from Prague to Vienna

You can purchase your ticket once you are in Prague. You can also purchase it right before your travel but to avoid stress in the case of long line there I prefer to buy it one to few days ahead. First class costs 50 % more than second class. IMHO upgrade is not worth it.

I purchased my ticket from Prague to Vienna about a month before our trip. It did save us some money, although I don't think it was more than maybe 5 or 6 euros. We took the second class train and found it to be very comfortable and clean. We had a little "room" that had six seats. Only two others came into our "room," so there was plenty of space for everyone.

If you do purchase in advance from the US, be sure to print your tickets on the proper size paper (the Czech train authority requires A4 size paper, which is just larger than standard 8x11). We just asked the front desk at our hotel in Prague to print them for us, and it was no problem.

I've never printed a ticket from the Czech web site, but other western countries' tickets do print fine on 8.5 x 11" paper; no necessary info is cut off. Instead of going to the train station in Prague, it may be handier to buy the ticket at the Čedok travel agency, one location at Na Příkopě 857/18.

I had looked into whether it would be a problem if we didn't print on A4 paper. My internet research yielded mixed results. Some indicated that they had no problems with standard 8x11, while I read a couple of stories where the ticket inspectors forced the individuals to purchase new tickets at the onboard price. So absent a real jerk of an employee, you probably wouldn't have a problem with the 8x11. But for me, it was worth taking the extra 2 minutes to ask my hotel's front desk to print them out for me on A4. When you buy the train tickets from the Czech website, they email your tickets in a PDF attachment, so this was very easy to do.