IMO, Slovenia is a hidden gem and worthy of much more time than you have to give it.

On top of which doing something half-baked (which is parlance for rushing through something
in a travel mindset) is often worse than not doing it at all.

Bratislava would be a nice day trip, and as you note, Budapest is charming (political status
notwithstanding). Melk Abbey is not that far away either.

Thanks, this is a fair point and I agree in principle, Slovenia clearly deserves more time, and doing it properly would mean slowing down and staying put longer. That said, one constraint for us is that we may not return to this part of Europe in the near future, so we are consciously leaning toward a breadth-over-depth approach, knowing it’s not ideal.

For context, based on some search from other posts, I was preparing this way:

Day 0: Arrive Vienna 8:00 PM, overnight

Day 1: Vienna --> Budapest (early train), afternoon/evening in Budapest, overnight

Day 2: Morning in Budapest, noon train to Graz, overnight

Day 3: Pick up car in Graz --> drive to Ljubljana, overnight

Day 4: Lake Bohinj --> drive back to Vienna, overnight

Day 5: Fly out Vienna 10:30 AM

We are aware this is rushed, especially Slovenia, and are trying to gauge whether this still makes sense for someone who is already seen places like Hallstatt and Lauterbrunnen, or if we would be better off trimming the loop and staying closer. We are prioritizing "better" over "slower", while trying not to make it needlessly exhausting

Appreciate the perspective, very helpful.

Edit - If I don't want to go so far towards Graz and Ljubljana, then another option I searched is this -->

Day-0 (June 17 – Evening): Arrive in Vienna in the evening, check into hotel, rest.
Overnight: Vienna.

Day-1 (June 18 – Vienna): Full day in Vienna for architecture and interiors (St. Stephen’s Cathedral, Hofburg area, Schönbrunn or Kunsthistorisches Museum).
Overnight: Vienna.

Day-2 (June 19 – Vienna --> Budapest):
Morning Railjet train to Budapest (~2.5 hrs).
Explore Budapest during the day and evening (Parliament, Fisherman’s Bastion, Chain Bridge / Danube views).
Overnight: Budapest.

Day-3 (June 20 – Budapest --> Vienna --> Wachau --> Český Krumlov):
Early train back to Vienna, pick up rental car.
Drive to Wachau Valley (Melk or Dürnstein for abbey/village scenery).
Late afternoon drive to Český Krumlov (~2.5–3 hrs).
Evening walk in Český Krumlov after day-trippers leave.
Overnight: Český Krumlov.

Day-4 (June 21 – Český Krumlov --> Vienna):
Morning exploring Český Krumlov (castle viewpoints + old town loop).
Afternoon drive back to Vienna (~3 hrs).
Return car.
Overnight: Vienna.

Day-5 (June 22):
Fly out of Vienna (10:30 AM).

The drive from Ljubljana to Bohinj via Škofja Loka is one of the most beautiful I've ever done. At several points I had to stop the car and get out and just gape at the amazing vistas.

Still, if I were in your position, there is no way I'd attempt to do what you are proposing. I'd limit my time to Vienna and one other location. I don't want to feel rushed, even for scenery that blows all other scenery out of the water.

But I'm not in your position. You are.

Each to their own, but I would limit it to Vienna and Budapest. If you did have to throw in a third, then Graz. But even that seems unreasonable, so:

0 arrive Vienna
1 Vienna
2 Vienna to Budapest early train
3 Budapest
4 Budapest to Vienna late train
5 Fly home

If that is too slow for you, then you stop at the archabbey in Pannonhalma and Györ on the way to Budapest and you stop in Bratislava on the way back to Vienna.

Thanks for your feedback.
I realized my days were less for this "long trip". I am able to find another flight, which would allow me to fly in Budapest and fly out of Vienna, in comparison to earlier fly in Vienna and fly out Vienna. Not sure, but will it relax it a bit but here is what I was able to draft based on hours of searching old posts -->

Option A: Austria / Wachau / Czech Republic

17-Jun – Arrive Budapest at night

18-Jun – Full day Budapest

19-Jun – Pick up car, Budapest --> Wachau Valley (Melk / Dürnstein), overnight Wachau

20-Jun – Wachau --> Český Krumlov --> Salzkammergut, overnight in lake region

21-Jun – Salzkammergut --> Vienna, spend evening in Vienna

22-Jun – Fly out of Vienna (10:30 AM)

Option B: Slovenia (Ljubljana + Julian Alps)

17-Jun – Arrive Budapest at night

18-Jun – Full day Budapest

19-Jun – Pick up car, Budapest --> Ljubljana, overnight Ljubljana

20-Jun – Lake Bled + Lake Bohinj, overnight near Bled/Bohinj

21-Jun – Drive to Vienna (with lunch stop in Graz)

22-Jun – Fly out of Vienna (10:30 AM)

=============

Out interest would be Photography (landscapes + architecture), scenic drives, cute villages / old towns, "Postcard-perfect" views

You did check the cost on the car, right? I could be wrong, but my first wild guess is about $900 rental and drop off fees, plus gas, plus tolls, plus 30euro a night to park, plus tickets, plus additional insurance.

Out interest would be Photography (landscapes + architecture), scenic
drives, cute villages / old towns, "Postcard-perfect" views

Probably the wrong tour. The architecture, yes, the Postcard-perfect views, sure in Budapest at the river; the rest ??? Hmmmmmm

I can only speak to myself. But if there is 5-hour drive ahead, I am not stopping much or for long. With a 3-hour drive it’s a different thing. So, with my temperament I would do this: https://maps.app.goo.gl/spteY2fXCFAjrV248 Tihany and Graz meet all of your requirements for why you are traveling as does Melk and the Wachau valley. Most of the drive is through wine country which is both beautiful and something I enjoy. Of course, renting a car you cant enjoy the wine.

If I wanted to see Slovenia I would start in Venice.

I checked only for rental price and that was around $550 for picking at Budapest and drop at Vienna.
Rest would be additional charges, gas, toll, parking, tickets and insurance.

Budapest is non-negotiable for wife and me, but rest all can be changed. We are at very initial stage and still relying on forum, posts and help, before we can lock in.

We are all different, so nothing is meant to say you are wrong about anything. That’s the problem with giving advice, its always going to be biased for personal tastes. If Budapest is non-negotiable then you are very smart (LOL - my current hometown).

Here are a couple more ideas.

Fly to Vienna, do at least one full day then rent a car and drive to Bratislava then to the Slovakian High Tatra Mountains. Why? A couple of Banska towns, freeking amazing castles, nature, cable cars to mountain tops, Strbske Pleso Lake. Enter Hungary at Kosice and into Budapest. No 5 hour bonzai drives, every km interesting. Fits all your requirements.

Next idea. You have already cast off the "slow down" RS forum nonsense. Go for broke and fly ... mid trip! Noooo! Did Mr E suggest travel sin!!!. Do a few days in Budapest then hop Wizzair someplace. Lots of opportunity to just be crazy and see something special. One easy choice is Montenegro. 1:15 flight time. Rent a car drive beautiful coasts and stunning mountains ... about 2.5 hours apart ... ohhh and lakes ... some of the largest in Europe and some of the most unexpected ... to me, looks Asian. Go to the Montenegro forum, a few posts have links to videos.

Tirana and the Albanian riveria is another option as is the Black Sea coast of Bulgaria.

Now I have two “too-good” problems 🙂
I spent a few hours thinking it through and talked it over with my wife, she’s fallen in love with Budapest and also with the scenery in Montenegro.
Since this trip is no longer centered on Austria, I’ll continue the discussion on the Montenegro forum.
Thank you all for the helpful suggestions!

Budapest and Montenegro are 2 of my 3 favorite places in the world. You cant do wrong.