It's worth flying via Budapest if you actually want to visit it, otherwise you'd be wasting time.

Generally speaking the must-see parts of Romania are southern Transylvania (the historic cities of Sibiu, Brasov, Sighisoara and the various castles, ruins, old villages around them, plus the spectacular southern Carpathian mountains) and the rural regions in the north (named Maramures and Bucovina; they have lots of traditional villages, ancient wooden churches, medieval monasteries etc.)

Being summer you should add a few days in the Danube Delta (unspoiled natural wetlands, lots of wildlife, picturesque fisherman's villages, relatively exotic deserted beaches at its Black Sea end).

All these areas (except Maramures) are closer to Bucharest than to Budapest. Southern Transylvania can easily be done using public transportation, for Maramures and Bucovina it's best to rent a car, the Danube Delta can only be done by boat.

In any case if you intend to rent a car it would be best to start and end in the same country: it's usually difficult/pricey to find car rental companies that would let you do a international one-way rental (like pick up in Budapest, drop off in Bucharest) in this part of the world - so if you rent in Budapest you'll most likely have to return it there.

Another thing to note is that there are international airports in several Romanian cities, not just in Bucharest. For instance you could fly into Cluj Napoca (via Frankfurt or London), it's reasonably close to Maramures-Bucovina and southern Transylvania.

Thank you for your quick and thoughtful reply. This is exactly the kind of info I was hoping for. And thanks also for the tip about flying into alternative airports.

Sandy (in Denton)

You might want to take a look at my trip report, although it is getting old; just click on my name to find it. We found that the cheapest rentals were out of Hungary, but we had to return the car in Hungary. On the other hand, for what we wanted to see, this did not represent a problem. We just did a circle tour of the Carpathians, starting in Maramures and ending in Timişoara.