18 days in Central / Eastern Europe

Too many destinations in too few days. Logistically Split is too far away, I would skip it this time. If you like slower pace then I would also skip Krakow. Then all your destinations are on a straight train line: Berlin, Prague, Vienna, Budapest. No zigzagging or backtracking. And you will have 5 days for Berlin (huge city) and 4 for each of the rest. Those are relatively big cities, too.

I would agree with IIlja on all points. We have been to all of these with the exception of Berlin and they are worthy of 3 days or more of sightseeing. It seems you will have a good amount of travel time in between. Even flying may not save you time depending on available flight routes and times. As nice as Krakow was you will be seeing some other great places and I would drop that. I would also drop Split as it is well out of the way. Hopefully you could return and include Split in an Adriatic countries trip itinerary. If you can end in Budapest and fly out of there instead of Vienna it will avoid you backtracking on part the same route from Prague to Budapest, if you are driving, as you would use to get from Budapest to Vienna. As was mentioned you could spend the extra time in these cities and/or have time to spend on some stops you find along the way.

Berlin - 3 days
Prague - 3 days
Krakow - 3 days
Budapest - 3 days
Split - 3 days (Mother really insists on this one).
Vienna - 3 days

Normally if someone wants to do something I at least try and figure out how to make it work, this one is beyond that. Prague to Krakow and Krakow to Budapest you can fly non-stop these days. And depending on the day of the week Split has flights to Vienna and Warsaw. That will help a bit i guess.

Get rid of Split and you have an "okay" trip. Get rid of Split and one of the others on the list and its a great trip.

Or if Split is a must then maybe fly into Budapest, train to Vienna, train to Prague, fly to Split and then home.

Thanks for the great responses guys.

It does seem a tad bit ambitious.

Unfortunately the flight out of Vienna is already booked, and it was chosen because it's a direct flight departing at a time that suits us.

If we do omit Split and Krakow, how do you suggest we spend those extra days?
Is there any way to make a route that starts in Berlin and ends in Vienna, that has some interesting spots along the way?

Leaving from Vienna has definitely limited us in some ways but my dad is very particular about flight departure times and only flying to places directly. He used to be a Pilot so I guess he's had his fair share of bad sectors and ungodly hours. :D

Berlin - 3 days, train to Prague
Prague - 5 days, I would suggest 2 of the 5 be day trips. There are some great options. Im not saying to use Viator but you can see some of the options. Then fly to Budapest (Czech Air is about $125 non-stop)
Budapest - 5 days (it is really worth the time). One day trip.
Vienna - 5 days with two days being day trips.

Some options out of Budapest include overnight trips to Eger and the wineries. Great town, great wine. Or an overnight to Pecs for the Ottoman history and a beautiful old town. Between Budapest and Vienna you could stay the night in Gyor with the great old town and visit the Archabbey at Pannonhalma and compare that to Melk (a good day trip out of Vienna)

Research the possibilities of overnights and day trips and adjust the days in each town accordingly...

Oh! Krakow, you can do that still

Berlin - 3 days, train to Prague
Prague - 3 days, then Fly to Krakow on Ryan Air non-stop
Krakow for 3 days, the fly to Budapest on LOT non-stop
Budapest - 5 days (it is really worth the time). One day trip.
Vienna - 4 days with one day being day trips.

Hey James, that's really helpful, and reassuring to know that it's a doable itinerary.

We were hoping to go by train the whole way but it does't seem like the options between Prague - Krakow - Budapest are that great. I really wish they get 300 km/hr high speed trains all over Europe.

Those flights are about $100 each and door to door about 3.5 hours. Not bad at all. Would take more time on a train.