Point to Point Travel, or RT Airfare?

You can usually get just as good a price with a multi-city airline ticket, say into Prague and return from Budapest. That saves time and money rather than backtracking. Just do a trial for flights in spring and check out the results.

I visited all three cities a couple years ago on a month-long trip and here’s what I can tell you…..
You can check www.Skyscanner.com for roundtrip and multi-city airfares from airports near you to see what fares look like one year from now as airlines generally sell seats up to 12 months in advance .

You can also get a quick idea of train fares and schedules between Prague and Vienna and Prague and Budapest and Budapest and Vienna at www.TheTrainline.com
However, the best deals on train fares can usually be found on the website of Ceske drahy— the Czech National Railway company: www.cd.cz/en. They will sell train tickets for trains traveling between the Czech Republic and its neighbors— Austria, Hungary, Germany, Slovakia and Poland.

Train tickets on that website for nonrefundable standard class tickets ( the ones I usually buy) can be bought for as little as US$25 from Prague to Budapest.
(Ceske Drahy usually has one early morning train that is significantly cheaper than all other long-distance trains). The trip takes about 7 hours and many trains stop briefly in Bratislava, Slovakia, if you were interested in visiting Bratislava.
In looking quickly at the Trainline, I see train tickets from Vienna to Prague—a 4-hour trip—-cost as little as $14 and $16 on the arbitrary date of December 3, 2024.

The other plus in buying the train tickets through Ceske Drahy is that the ticket price includes the seat reservation at no additional cost. Some train companies charge $10 for just a seat reservation.
Train tickets on the Ceske Drahy website go on sale 90 days in advance of the train’s departure date. Generally, the earlier you buy your train tix the less they cost for the long-distance high-speed trains.
To save money on airfares be sure to check airports close to your home city. For example, if your hometown is Savannah, Georgia you will want to check airfares out of Atlanta and Jacksonville. Florida.
I live in San Diego, so I check airfares out of Los Angeles and Orange County.
With train tix so inexpensive, focus on getting the best deal you can on your airfare. And, while a multi-city ticket might save some money and time— with a $16 train ticket from Vienna to Prague that only takes 4 hours— it may well be the least expensive flights will be if you fly roundtrip to and from Prague.
Let us know where you’re flying from and the approximate month and regulars here will have something to work with to help you plan your trip.
Cheers!

With three weeks you can see quite a bit.

Day 1 Depart for Prague
Day 2 arrive in Prague. First day is jetlagged and a mid-afternoon arrival
Day 3, 4, 5 in Prague (its a rather small tourist district and this is enough time to experience it. More time next trip if you fall in love.
Day 6 morning Shuttle to Cesky Krumlov. (there are two that do door to door service for a reasonable cost) Great little tourist town, but it is a tourist town. But most tourist leave about 2pm and the city is great after that .... until about the time you head on to Vienna.
Day 7 late Shuttle to Vienna
Day 8, 9, 10, 11 12 in Vienna, including a day trip to Bratislava or any number of other places.
Day 13 morning Train to Gyor / Pannonhalma Archabbey (this is on the rail line that goes to Budapes so its not out of the way and its a lovely smaller town and the archabbey is very interesting)
Day 14 early evening Train to Budapest.
Day 15, 16, 17, 18, 19, 20 in Budapest with an overnight trip to Eger for the town and the wine country. Eger is about 2.5 hours by train. No one ever visited it and regretted it)
Day 21 Fly home from Budapest

So, the side trips you can do what ever interests you. Do some research. There are other scenarios. If you just wanted to stay in the cities the most time effective is to fly from Prague to Budapest (discount airlines start at under $50 but depends on your luggage) then train to Vienna and head home from Vienna. A week in each isnt a terrible idea. Ehhhhhh, a week is a tad long for Prague for my taste. 25% Prague 35% Vienna and 40% Budapest (its the largest of the three).

The open jaw ticket doesnt always cost more. Try running it in reverse too. Even if the ticket does cost a hundred or so more, the fact that you save an entire day of travel more than makes up for it. More value touring for the money spent.

Remember, you are not searching for two one-way tickets, you are searching for a single multi-city ticket.

https://thriftytraveler.com/guides/best-day-to-book-flights/

That ThriftyTraveller article advises the best time to buy international flight tickets is 2-6 months before the departure date.

Thank you everyone for your answers. It's hard to believe I had never heard of multi-city airfares! I'm sure I'll benefit a lot from this forum.

I do not quite agree with Mr. É (confused) regarding the travel schedule he has given. I would take 2 days at least from Budapest and give it to Vienna. The argument that Budapest is bigger is tenous. It is true for the area, but not for the population, the number of museums, the sights and cultural offerings, IMHO. (Having been in both cities several times, I am biased for Vienna, as much as Mr. É for Budapest.)

wmt1 yes, I am biased "having been in both cities several times" I usually state that with suggestions but forgot this time. By the way, for those that dont know, Magyarország (you will see under my name) is the Hungarian name for ............ well Hungary and is my current place of residence. Its why I talk so much about Budapest. Its one of the few places I know enough to be accurate with. But this discussion has no accuracy, its all about personal preference and what you like and dont like. So my living here has not value in the discussion. To respond to your comments …. All correct by the way …. It’s just a matter of perspective and what interest you vs me that is different (our bias).

Vienna: If you google "tourist map of Vienna" the vast majority of what the common tourist goes to see lies within or on the outer perimeter of the Ringstraße. That area is about 1.5sm. A similar google for Budapest, will show that the majority of what the common guy goes to see is within the 1900 border of the city Pest + the Castle District in Buda. An area of about 10sm. In both cities, the little things and the architecture and the environment between the major sights is as interesting as the sights. So if you define sights by points on a map, Vienna might win. If you define the extent of the experience, I give a large edge to Budapest. That was the premise of my "Budapest is larger comment" by about 7x in fact. But doesn’t matter how large something is, if you aren’t interested in it.

Museums, wmt1 absolutely, if you are a museum hound, then Vienna is the place to be. You could easily spend all day every day for several weeks doing nothing but museums. Few cities can compete, not even Budapest.

Cultural Offerings. This one is also a matter of perspective. If you want the finest of the classical cultural offerings, then Vienna wins. If you go to the opera in Vienna you will among people who have traveled from all over the world to see the show. If you want to be within a culture where classical offerings are a daily part of life for people from all incomes then Budapest wins. If you go to the Opera here, it will be sold out, it will be better than the vast majority anywhere in the world and the majority of those sitting with you will be Hungarians. Just a different perspective on the same topic. Both valid.

Generally speaking half of all tourist enjoy both Vienna and Budapest equally but differently. The other half are the fantics.

Thank you, Mr. É, I agree. That was exactly the response I intended to provoke. :-)

A main problem is the lack of time tourists usually have, especially US tourists (if not retired) having only 2 weeks annual leave for vacation. Europeans are more relaxed, usually having 4 or 5 weeks paid annual leave. Consequently, most tourists concentrate on the major sights, only. To get a real feeling for a city like Vienna an Budapest you have to come several times.

wmt1 my post was on topic as the information may help in the planning process. Your last post was off topic. This is a discussion for a different thread.

Fall of 2025

Yes, too soon to book. You can still look at the RT vs Multi-city fligth and price options on Google Flights or any other site you choose. Just pick a date in mid-December. It will give you a feel for what prices may be and will let you see connection and airline options. Based on where you are traveling from in the US you may find that one of these cities is best for going to and the other best for coming from.

And, if you are going to use the train you will find that Vienna is right between Prague and Budapest. To spend the least amount of time on trains you will want Vienna as your second city, with Prague or Budapest first or third. Or if you want to see Eastern Czechia and Slovakia, then you can do trains that don't pass through Vienna.

I have been to and think all three are wonderful cities. IMO Vienna is the best for museums, palaces, parks and the culture of a very green and livable city. It does have the least Medieval sites.