Some of the week-ends, the traffic on Prahova valley, between Bucharest and Brasov, might become a nightmare. The train is the appropriate solution. There are now some good trains, clean and cheap, run by private and public companies.
or Astra Trans Carpatic
and from Bucharest you would be in Sinaia, for a visit to Peles Castle
for example, in 1h30mins., while with Regio Calatori
it takes 2h15 mins. but very cheap (around 4 euros).
For about an hour, from Campina to Brasov, the views over Bucegi
and Piatra Mare
massifs are simply amazing.
On TRANSFAGARASAN Mountain Road to the HEART of TRANSYLVANIA