🚂 Trains (4 legs): Sofia→Plovdiv (bdz.bg), Bucharest→Brașov (cfrcalatori.ro, ~2.5 hrs), Brașov→Bucharest (cfrcalatori.ro, ~2.5 hrs), Veliko Tarnovo→Sofia (bdz.bg, ~3.5 hrs).
🚗 Rental car (1 leg): Plovdiv→Bucharest via Top Rent a Car (toprentacar.bg). Crosses Danube at Ruse border, ~5 hrs.
🚐 Daytrip.com (1 leg): Bucharest→Veliko Tarnovo (~3 hrs). Private driver, can add sightseeing stops (Ivanovo rock churches, Basarbovo Monastery).
Still to book: All transport (trains + Daytrip).