Trains go across all over Romania - they are the fastest and safest way of travelling, since roads are in a very bad shape and full of cars
Here is the trainschedule: http://www.cfr.ro/ The next means of travelling are the public buses - from Bucharest they go around the country to all cities; the drivers are proffessionals, they always reach in time the destination: check some websites of the main routes and companies:
http://www.autogari.ro/Companie/TRANSMIXT/1095.aspx http://www.autogari.ro/Transport/Cluj_Napoca-Alba_Iulia/11182-1.aspx
http://www4.pmb.ro/wwwt/wwwcs/inf_util/ritmului.htm
http://www.autogari.ro/Bucuresti/Autogara_Obor/Autogara74.aspx
http://www.autogari.ro/Bucuresti/Statie_Baldovin_Parcalabul/Autogara162.aspx
And of course the internal flights to the main cities: Sibiu,Cluj, Timisoara,Iasi through TAROM
Another way is to rent a car, but you will pay for every scratch, so is by far the most expensive way of travelling