Any and all recommendations for a rail trip from Budapest to Istanbul would be greatly appreciated!
The German Rail website probably has the most comprehensive database for European rail travel. They basically show only one connection for any 24 hour period. It includes a 23 hour connection from Beograd (is that what we call Belgrade?) to Istanbul. It leaves every morning at 7:50, arriving the next morning a 7:50 (must be a time zone change). To catch the train from Beograd to Istanbul, you need to take another night train from Badapest. Total time is about 31 hours. Happy traveling.
Thank you for the quick response!