Romania / Bulgaria...Friendly advice for a fast traveler

You have to actually look at the train schedule and distances between the cities...that will answer your question as to whether it's feasible or not. Trains in Romania are extensive, but they are slow - 30 miles an hour, so be sure to factor that in. If you're tight on time, consider renting a car.

http://romaniatourism.com/sample-itineraries.html

To get to Bran Castle you have to take a train to Brasov, and then get a bus or taxi. It's about 30km. I don't know about buses that run directly from Sigisoara or Sibiu, but I'm sure you have some options.

Sigisoara, Sibiu, Brasov, and Bucharest are connected by a fairly slow train service so you'll be spending longer on the train than you will elsewhere in Europe. I was much more impressed by Peles Castle than Bran, but your tastes may vary. Both are in picturesque areas. Peles Castle is near Sinaia which is a train stop on the way to Bucharest. I was very impressed by Sibiu and spent one evening, and most of the next day. I could have spent longer.

It's easier to drive between these places, but then it's a question of your comfort driving there, and the roads can be slow too. I'm guessing that you are not keen to drive, but depending on the time of year you could experience a drive along the Transfăgărășan (https://en.wikipedia.org/wiki/Transf%C4%83g%C4%83r%C4%83%C8%99an).

I'd take a day in the quirky Bucharest if you can spare the time. I don't know about Bulgaria so hopefully others can help you with that.

Have fun!

For some it's about the sights, for others it's the journey. For you it seems to be the journey, and that's excellent if it works for you. I did that once when younger and have no regrets. You did pick a couple of difficult countries to move quickly through. But think of it this way, the longer it takes to get from A to B, in a very profound way, the further apart they are. So in a bizzare sort of way you are traveling quickly. I love Romania and Bulgaria, so I think you have chosen well. Do your homework and talk to lots if people along the way and have a great trip.

Take heed of the others' warnings about slow trains and buses. Use rhe Deutsche Bahn website to check on trains. For buses, start with Rome2Rio, but you must drill down till you get to the name of the bus company providing service, then go to its website to find the schedule. Do not trust the fares or trip times given by Rome2Rio.

I spent very little time in Bucharest and Sofia, not really enough to give them a fair chance. They're probably necessary for logistical reasons, anyway. I very much enjoyed Timisoara, Sibiu, Brasov and Sighisoara (touristy). In Bulgaria I much preferred Plovdiv and Veliko Trnovo to Sofia.

Thanks very much, this is exactly the insight I was looking for and have come to expect from the Forum. My current thinking is that this corner of Europe deserves a few more days than I maybe am able to spare this time around. I'll make my final decision soon. Thank You very much!

Deserves a couples of weeks. We rented a car and driver and it was very cheap and most worth it.
See my personal pics at:
http://www.gadtravel.com/2015/11/romania-and-bulgaria_19.html

Oops, thanks

This was many, many years ago, but we needed a week to see a bit of Bulgaria, driving a rent-a-wreck VW, then took a sloooooow overnight train into Bucharest. When you visit Bulgaria, if your time allows, consider also going to Veliko Tarnavo. Happy travels!