Quick Rundown, in order:
Flew into Athens, immediately rented a car
Drove to Meteora, 3 nights
Delphi, 1 night
Drove to Athens airport via Lake Vougliameni and Sounion Peninsula, Returned car, Taxi into Athens
3 nights Athens
Flew to Sofia, immediately rented a car
Belogradchik, 2 nights
Sarmizegetusa, Romania 1 night
Drove to Sibiu via Huneadora and Sarmizegetus Regia, stayed 2 nights
Sighsoara, 1 night
Brasov, 2 nights
Sinaia, 1 night
Ivanovo, Bulgaria, 1 night
Veliko Tarnovo 2 nights
Plovdiv, 2 nights
Drove to Sofia, visited the city, and returned the car at the airport.

Expenses:
I stayed at some guesthouses in Romania and Bulgaria. For eight nights in a row we were without A/C. Only missed it one night. Both countries just as hot during the day as Greece, but cooled down more at night. Greece much less expensive than Western Europe. Bulgaria and Romania more so. Food is inexpensive. We could have saved even more money on food by not over-ordering. But who can resist? Low prices and large portions. We often ordered a salad and two other items, but it was too much food. Gas and car rental same price as Greece.

Glad you liked the pics!

I use a weather/climate website to look at temperature, precipitation and the like. Looks like September is significantly cooler than July, the hottest month:
https://www.climate.top/bulgaria/plovdiv/index.php

shelemm, so enjoyed your TR and stunning pictures. Greece of course is an old favorite, I particularly loved your images of Meteora. We should have gone on earlier trips but somehow never made it, two years back we didn’t have enough time, plus DH’s knees would have found it tough.

I have never considered visiting Romania and Bulgaria, but you have made me think of it… would definitely like to fit it in on one of our future trips, but there are already so many other places I want to see!

Thanks!
I know, there are so many fascinating and wonderful places to go. I try to think of what my next priority is.

For folks who can't climb up stairs, there are many amazing views from the road that connects all the monasteries, and there is one you can access without stairs. For that one you must get there first thing, because it's also the most visited. The towns of Kalastraki and Kalabaka are notable for how close people live to these amazing rocks. It was fun to just walk around town and to go into the neighborhoods.

shelemm,
Many thanks for outlining your itinerary for me and also for the expense/cost information. And thanks for the weather link!

Belogradchik magical place one of my favorite places.
Also is nice to Visit Vidin and the Baba Vida Castle.

Bansko is also very historical town.

I'm late to the game, but WOW! What a wonderful trip report. My husband and I are considering a driving trip next year to Romania and Bulgaria, so I just now found this. A few questions for you:

- Any issues with the rental car company in taking the car across the border into Romania? I think I read somewhere that it can be problematic if you rent a car in Romania to take it to Bulgaria - but not the way you went? We had thought of starting in Bucharest, but really like the way you did it.

- It appears you skipped Bucharest completely - although you drove right by it. Is that right? And why?

- I know you can't "see it all" but you didn't go to the Rila Monastery? Why did you elect to skip that? (Or did I somehow miss it?) We'd also like to see the Rila Seven Lakes. If you had more time, would you have included these things?

- We would like to include Maramures. It's definitely out of the way - would mean about a 4 hour detour up and back. Did you initially consider trying to include it?

Thanks again. Such a well-written report with lovely photos! I really enjoyed reading it.

Thanks for the kind words althom1122 .

No issues with crossing the border. When you reserve the vehicle, you tell the car rental company which other countries you will visit, and they charge you for the medallion (I forget the correct term) which pays for the road tolls. It is seamless. In principle, should be even easier these days, now that they have 'opened' the border since my visit. Definitely use a well-known and established car rental company for these countries.

Bucharest - I had no interest. Seeing the excesses of Ceausescu repulses me. Same reason I had no interest in driving the tranfagarasan. I am sure there are other reasons to visit, but it would have been a super low priority. Even though I got to see some of Sofia, I did not spend a night and do not regret it. What I did see was disappointing.

Yes, I skipped Rila, which is considered a highlight of Bulgaria. I tried to fit it in. I had already planned on visiting the six monasteries of Meteora just before, so I was willing to jettison this even though I am sure it is magnificent.

There was no way I was going to squeeze in Maramures. It is the kind of area I love to visit, but I'd need more time up there than I had.

For me, it was a perfect trip. Except I probably should have taken away a night form Brasov and devoted that to the route between Veliko Tarnovo and Plovdiv. I wound up missing Tryavna, which I had planned to see.

Two things I wish I knew about before going:
You can arrange a lunch in advance at Alma Vii fortified church.
There is lodging on the royal estate at Peles Castle.

Hope this helps.

Thanks so much for the response. We're not really into big cities (like you, we prefer small towns and off-the-beaten path destinations), but I don’t want to completely skip the capitals so I think we'll allocate a day each to Sofia and Bucharest (although I hear you on Ceausescu).

Your report tipped me off to a number of locations that I wasn’t aware of, so I really appreciate that! You have a real talent for writing about your experiences - and your photos really bring it to life. Now I REALLY can’t wait for our own trip!

By the way, we went to Greece several years ago and did your exact land itinerary (and then added Naxos and Santorini). We loved Meteora - and I think we may have stayed in the same hotel you did!

Thanks again!

I would like to add that we visited Romania this past September. I plan on writing a TR but probably won't have time until after the Thanksgiving holiday. We did spend 2 nights in Bucharest, and we enjoyed it very much. We had about 1.5 days there. There are a couple of museums I was interested in seeing but they were closed the 2 days we were in Bucharest. However, we thoroughly enjoyed walking down the main Boulevard, Victorei Boulevard, all the way to Old Town. There is some pretty architecture on Victorei, and the Old Town has some pretty architecture, too. There are lots of restaurants and cafes, and we spent a couple hours sitting outdoors at a cafe, relaxing, and having a grand time people watching. The Biserica Stavropoleos in Old Town is small but stunning! One of our best meals was at Caru Cu Bere in Old Town. The interior is filled with old world charm, but we preferred sitting outside and enjoying the lovely evening.

If you have the time, I highly recommend going to Maramures to see the wooden churches and prison/museum at Sighetu. We also loved the painted monasteries in Bucovina, if you have the time.

Although I didn't mention it in my trip report, I felt that visiting the Boris Denev State Art Gallery in Veliko Tarnovo gave me a great indication of Bulgarian Art and Architecture. And walking the oldest street of VT, ul. Gurka, which is lowest to the river, was also a joy. My favorite place to eat is there as well as a wonderful house-museum.

@KarenWoo did you drive or had a car + driver for Maramures and Bucovina? We are considering a similar trip next year, but are not sure about driving in Romania.

xyz99, we rented a car for our entire stay in Romania. My husband was the driver, and he did not have any problems. For the most part, the roads are fine. There were a few places with potholes but not many. We spent 17 nights in Romania and 5 nights in Budapest. I don't know when you plan to make your reservations, and I will cover this information in my TR but I might not have it ready in time for you. We flew into Iasi, Romania, where we picked up our rental car. I got this idea from KJA's report. Then we returned the car to Bucharest. This way we didn't have to drive north from Bucharest and then turn around after visiting Bucovina and Maramures to drive south to Transylvania.

Driving in both countries is very easy with polite drivers. I didn't see an accident in my two weeks. Compared to driving in the US, you will be relieved at the lack of aggression.

For our 3-week trip in September, I am now considering dropping Plovdiv and instead spending 1 night in Koprivshtitsa, 1 at Rila Monastery (will try to get overnight reservations in the monastery), and the final night in Sofia - after a 2-3 hour stop at the Seven Rila Lakes. We don't like driving in cities, and are concerned that Plovdiv would be difficult. I can tell you loved Plovdiv, but what did you think about driving there?

It was easy to drive in and out of Plovidv. We spent 2 nights in Plovdiv, and our hotel was located in Old Town right where there is a gate set up to enter Old Town. Since we had a reservation, we were allowed to pass, and our hotel and street parking was just beyond the gate.
Nothing could be easier, though I didn't know about the gate beforehand, so that was a surprise. We stayed at Hill House, and it was extremely nice.

We did not have to use the car while we were in Plovdiv, and that would be true even if we were staying longer.