Itinerary Germany/Austria/Slovakia/Hungary

I would do like this. Instead of a day trip to Salzburg, spend 2 nights there. Then to Hallstatt midafternoon and spend a night and do the salt mine next day. then midafternoon depart for Melk and spend a night. Finally midafternoon head to Bratislava for 2 nights. So it would look like this.

Tuesday, October 15, 2019 Travel to Salzburg
Wednesday, October 16, 2019 Salzburg
Thursday, October 17, 2019 Travel to Hallstatt
Friday, October 18, 2019 Travel to Melk
Saturday, October 19, 2019 Travel to Bratislava
Sunday, October 20, 2019 Bratislava

There is some advantage to not fighting the day-trippers by getting there the day before late afternoon. You travel Salzburg to Hallstatt to Melk to Bratislava with Einfach-Raus Tickets without sacrificing much travel time. For Bratislava, just buy the added fare from the Austrian border.

Honestly, this itinerary doesn't make sense to me.

Stay in Salzburg from Oct. 15 - 17, visiting Hallstatt as a day trip.

Skip Melk. It is a nice day trip from Vienna, but not really an entire destination unless you are spending a few nights to explore the region. What do you plan to see - the abbey? You're missing the best part of that region, then, which is the villages and charm of the Wachau Valley. Kind of off the path on the main railway line as well. October is likely to be cold and rainy.

Bratislava - meh

Here's what I would do -
Tuesday, October 15, 2019 Travel to Salzburg, sleep in Salzburg

Wednesday, October 16, 2019 - Day trip to Hallstatt, sleep in Salzburg

Thursday, October 17, 2019 - Salzburg, sleep in Salzburg

Friday, October 18, 2019 - Travel to Wachau Valley; sleep in Duernstein, Weissenkirchen or Spitz

Saturday, October 19, 2019 - Wachau Valley; sleep in Duernstein, Weissenkirchen or Spitz

Sunday, October 20, 2019 Travel to Budapest (or detour to Bratislava but 2 or 3 changes will be required)

Thinking about dropping Bratislava and slowing down the trip some. What do you think about this?

Also If I was to change Salzburg back to a daytrip and spend one night in Hallstat I could add Bratislava back. Not sure? Anybody had experience with arriving in Hallstat and doing the salt mine the next before the leave for Melk.

I have presented both ideas below.

Option 1

Friday, October 11, 2019 Leave USA

Saturday, October 12, 2019 Munich

Sunday, October 13, 2019 Munich

Monday, October 14, 2019 Castles Daytrip

Tuesday, October 15, 2019 Travel to Salzburg

Wednesday, October 16, 2019 Salzburg

Thursday, October 17, 2019 Travel to Hallstat

Friday, October 18, 2019 Hallstat

Saturday, October 19, 2019 Travel to Melk

Sunday, October 20, 2019 Melk

Monday, October 21, 2019 Travel to Budapest

Tuesday, October 22, 2019 Budapest

Wednesday, October 23, 2019 Budapest

Thursday, October 24, 2019 Budapest

Friday, October 25, 2019 Fly Home

Option 2

Friday, October 11, 2019 Leave USA

Saturday, October 12, 2019 Munich

Sunday, October 13, 2019 Munich

Monday, October 14, 2019 Castles Daytrip

Tuesday, October 15, 2019 Day Trip to Salzburg

Wednesday, October 16, 2019 Travel to Hallstat

Thursday, October 17, 2019 Travel to Melk

Friday, October 18, 2019 Melk

Saturday, October 19, 2019 Travel to Bratislava

Sunday, October 20, 2019 Bratislava

Monday, October 21, 2019 Travel to Budapest

Tuesday, October 22, 2019 Budapest

Wednesday, October 23, 2019 Budapest

Thursday, October 24, 2019 Budapest

Friday, October 25, 2019 Fly Home

Sycthian - completely agree. Makes no sense.

Also, getting from Hallstatt to Melk? That will be a roundabout day of travel.

Option 1 would be my choice.
Hallstatt to Melk is 3 to 3 1/2 hours using an RJ train for one of the legs. 4 to 4 1/2 hours using an Einfach-Raus Ticket with all regional trains.

You travel Salzburg to Hallstatt to Melk to Bratislava with Einfach-Raus Tickets without sacrificing much travel time.

I do not agree. The ERT confines you to slower local trains. Given the distances you want to travel you should use express trains whenever available.

Although I do not fully understand why someone might want to skip Vienna, I would stay longer in Salzburg and shorter in Budapest.

Bratislava's historic center can be explored in less than day, so an overnight stay is not feasible. As the train connections between Bratislava and Budapest have been improved (several direct EC EuroCity express trains per day) you may visit Bratislava on your way from Vienna to Budapest. (Coming from the west you will go through Vienna anyway.)

OK....after looking at it some more and seeing what sites last time I missed in Vienna...I think this or something similar is what I want to do....What do you think?

Friday, October 11, 2019 Leave USA

Saturday, October 12, 2019 Munich

Sunday, October 13, 2019 Munich

Monday, October 14, 2019 Castles Daytrip

Tuesday, October 15, 2019 Travel to Salzburg

Wednesday, October 16, 2019 Salzburg

Thursday, October 17, 2019 Daytrip to Hallstatt

Friday, October 18, 2019 Travel to Vienna

Saturday, October 19, 2019 Vienna

Sunday, October 20, 2019 Daytrip to Melk (morning at the Abbey and the boat to Krems then train back to Vienna)

Monday, October 21, 2019 Travel to Budapest

Tuesday, October 22, 2019 Budapest

Wednesday, October 23, 2019 Budapest

Thursday, October 24, 2019 Budapest

Friday, October 25, 2019 Fly Home

Bratislava is really only good if you want to knock another country off your travel list. I've been to Vienna several times and would always opt for another day in Vienna as opposed to Bratislava. I also think you are not giving yourself enough time in Salzburg. I found Hallstadt interesting to visit. Once. For day trips out of Salzburg I'd always repeat visits to train hopping all the way to Berchtesgaden and back. Or the Pongau region or Bad Gastein.

Have a great trip!

I would agree dropping Bratislava.

Hallstatt would be dropped too since that place is of no interest to me. Spend the dropped time in Budapest or Salzburg instead.

Lots of good thoughts shared here--as I am accustomed to seeing. I/we have seen parts of your journey in visits of 1999, 2005, and 2012. We saw Hallstatt in a day-trip from near Salzburg, and didn't need more than that. Before you commit to that visit, BE SURE the mine tour is open -- at a point in the year, that ends. We were just 4 nights in Vienna, and are going back this year for more. We figure Bratislava to be a day trip by water, as it holds little of interest for us, but now we can say we were a second time in Slovakia. Extending time in Budapest sounds great, as the short visit there on the RSE Eastern Europe tour was too short. Be sure to swim in one of the hot baths there, maybe the one NE up the subway about 10-12 stops from downtown.