We are considering taking this trip in mid-August and flying into Budapest (5 nights)and taking the train (RailEurope #66 Budapest Keleti to Wien Westbahnhof Vienna=close to our hotel)for 4 nights, then take the train (from Wien Meidling to Prague Praha Hlavni Nadr #70)then 5 or 6 nights in Prague. What is someone's opinion about our buying the tickets at the stations when we get to Budapest or should we purchase them on line before we leave? We are traveling mid-day so what is the chance of the trains being full? Thank you for any information pertaining to our plans.

In France, in pays to buy the tickets early for discounted prices. That is also true in Italy. You could check and see if that is the case for the itineraries you anticipate. Do a reservation for next week without finalizing it, and for three months hence, also without finalizing it. But you should be able to see if there is a price differential.

I highly recommend a night or two in Cesky Krumlov between Vienna and Prague!

There are shuttle services that can get you between Vienna and CK.

When you arrive in Budapest go and buy your train tickets. Same when you arrive in Vienna. That should get you the best rates. Trains are rarely full.

its definitely better to buy the tickets ahead

when in Budapest be sure to check out the jewish quarter (http://jewish.hu/view.php?clabel=tortenet), the castle district (http://en.wikipedia.org/wiki/Buda_Castle) and the spas (http://www.ticket.info.hu/en/program/baths-of-budapest)