Train Travel - Amsterdam to St. Goar to Würzburg to Frankfurt

"Is this itinerary possible to do via train travel?"

Absolutely. As long as you have enough time in each place for your day trips.

"The hardest part is figuring out how to get from Amsterdam to St. Goar."

From: Amsterdam Centraal
To: St Goar (Do not type a period after St.)

Use the above names at the DB itierary page for your travel dates.

The day trips from St. Goar and Würzburg can be done using day passes purchased locally. Figure less than €30/day/couple. The day pass in St. Goar will cover the ferry across the river for train rides to Braubach and Rüdesheim.

Monica, Yes it is possible.
What problem are you having with bahn.de ? Did you switch it to English ( https://www.bahn.de/p_en/view/index.shtml )?

• Enter "Amsterdam" and it will suggest "Amsterdam Centraal"
• Enter "St Goar", and a date and a time and click on "Search".

And it gave me lots of options. For example (for a random date in December):

Amsterdam Centraal dep 08:02 7 ICE 105 Intercity-Express Direction: Basel SBB
Köln Hbf arr 10:45 6
Transfer time 11 min.
Köln Hbf dep 10:56 9 D-G RB 25421 MittelrheinBahn (Trans Regio) Direction: Mainz Hbf
St Goar arr 12:55 2

Amsterdam Centraal dep 10:37 2 ICE 123 Intercity-Express Direction: Frankfurt(Main)Hbf
Köln Hbf arr 13:15 6
Transfer time 41 min.
Köln Hbf dep 13:56 9 D-G RB 25427 MittelrheinBahn (Trans Regio) Direction: Mainz Hbf
St Goar arr 15:55

Later trains at 12:37, 14:37.

Same for your other trips. If you can say what problems you are getting with bahn.de, we can help you solve them.

For day trips out of St Goar, you can buy VRM day tickets out of the station ticket vending machines. St Goar to Cochem and return in a day is a "Minigruppenkarte" for 22.10 EUR. Travel after 9 am on weekdays, all times on weekends on regional trains. Ditto St Goar to Braubach. It covers 2 to 5 people traveling together.
For St Goar to Ruedesheim, buy a Rheinland-Pfalz Ticket for 29 EUR. Same restriction as the VRM ticket.

Wuerzburg to Bamberg can be done with a Regio-Franken-Thueringen Ticket for 25 EUR.
Wuerzburg to Nuremberg can be done with a Bayern Ticket for 28 EUR.
Wuerzburg to Iphofen is a VVM local transport ticket. Looks like 20.20 EUR for a Family Tageskarte Plus will work. You can ask when you get there.

Standard rules apply to all these tickets, mainly M-F after 9 am, Weekends and holidays good all day, must use regional trains (or buses if need be). Bayern Ticket also works on the Nuremberg U-Bahn.

Amsterdam, St. Goar, Cochem, Braubach, Rüdesheim, Würzburg, Bamberg, Iphofen, Nürnberg, & Frankfurt

All those towns have train stations, and they are all interconnected. I've been by train to all of them but Rüdesheim and Iphofen.

The Bahn website is not hard to use. It even has an "ignorance algorithm" which help you find towns if you misspell them (as long as you don't correctly spell the name of another town). Example, if you type in St. Goar (with a period), it will suggest a number of places. One will be St Goar (without the period), which is the Bahnhof in St. Goar. Another is St Goar KD, which is the dock for the K-D boats, on the river, a few blocks down the hill from the station. The third suggestion is St Goarshausen, across the river from St. Goar. Others on the list are bus stops in those towns.