Germany Itinerary

Sept 7. You can keep your options open buying a Quer durchs Land ticket and travel by all regional trains that day. You can stop off in Heidelberg and see how it looks. There are around 3 regional departures every hour that will get you to Bad Cannstatt in about 2 1/4 hours. So you can check out the lay of the land and continue to Bad Cannstatt when you decide its time to move on.

Since distances are relatively short, you don't save a whole lot of time using fast trains, but keep maximum flexibility.

Similar strategy at Ulm. With a QdL, leave after 9 am. There is a direct regional train at 9:33. At Ulm, there is a Regional Express train to Munich every hour and it takes 2 hours to get to Munich, 45 minutes slower than an ICE train. Then you can take as long or short a time to climb the Muensterturm as you like.

Your itinerary looks great to me. Strong work on putting together a well-paced trip through Germany! A few thoughts:

Stuttgart stop: The question of when to visit Heidelberg has no right or wrong answer. It's just a matter of preference and weighing advantages/disadvantages. For example, are you looking forward to a peaceful, contemplative walk on the Philosopher's Way? Monday is probably going to give you a better shot at that than Saturday or Sunday.

Munich stop: I have never been to Ulm, so I can't answer the cathedral question. For me, Marienplatz and the Viktualienmarkt are not big time eaters. If you are interested in WWII history, consider doing a WWII/Nazi tour with one of the local companies. I'm also from a fairly rural area, but I think the Englischer Garten is great -- for walking, people watching, surfer watching etc. A city of 1.45 million people should offer plenty to fill 3+ days, but many people do day trips to see something other than the city. I've only spent 3 nights in Munich, so, sadly, I'm not a good source for hidden gems there.

Frankfurt train day: Yeah, sounds like a long trip, but I wouldn't say miserable. Take a good book; look out the window frequently; enjoy a mode of transportation most of us in the US (if that's where you are) don't get to enjoy.

The International Car Show is happening in Frankfurt from 12-22 Sept. so you will struggle to find a hotel room available, let alone one you can afford.
Only suggestion is to stay more than 50km outside of the city and train in on the morning of your flight or check with the city as they often have blocks of rooms set aside for tourists that may be cheaper.
www.frankfurt.de

Well, I've never heard of anyone choosing Bad Canstatt until recently, but I actually think it's a great idea. While the area around the train station is ugly, and some find it shady (it's just busy and diverse) Bad Canstatt has a surprisingly charming old town, a biergarten on the river, and the best Greek food I've had in Germany due to it's large immigrant population - and yes, good transit connections.

Stuttgart also gets a bad rap in terms of international travel, because it largely wasn't rebuilt in a historical style after the war, but I still think the Schlossplatz is the most beautiful city square of anywhere in Germany, and having two castles next to each other right downtown is definitely cool. Unfortunately a lot of the city's charms are somewhat hidden - so it's easy for a tourist to come, shrug, and move on.

You'll be here during the biggest festival held in the city center, though - the Stuttgart Wine Village. It's not just about wine, but also the Swabian cuisine, as local wineries and restaurants set up charming booths throughout the city's other two main squares (Schillerplatz and Marktplatz). You're really lucky to be in town for this!

As for stopping in Heidelberg, I personally would, because why not? Yes, it will be crowded, but Heidelberg is different enough from your other destinations.

I don't think 3 full days is too much for Munich if you plan on visiting any of the city's excellent museums. No interest in Nuremberg or Salzburg? They're both worthy day trips in my book.

As for tickets, it depends on your style of travel. As others have noted you can buy day tickets that allow you to take the regional trains for a very low price. You can also buy high speed train tickets for some routes in advance to save money, but you're then locked into that specific train. I use a mixture of both to get around, but for example, Munich is reached in 2:12 from Stuttgart on the fast ICE train, or 3:18 with one change in Ulm on the regional slow train for which you could buy the day ticket (Quel-Durch-Lands ticket).

Thanks for the replies!

Sam, I may take your advice and buy a €44 Quer-durchs-Land ticket for the first Saturday (St. Goar to Bad Cannstatt), but I like to get on the road early, so I think I'll avoid those tickets on weekdays. If I wait until 9am to hop on a train, I'll feel like I've wasted the entire morning.

I'm testing different connections on Bahn.com right now and finding something odd. A ticket from St. Goar --> Heidelberg --> Stuttgart is €4 cheaper than a straight ticket from St. Goar to Stuttgart. The Sparpreis is €35.90, which seems like a pretty good deal. The only problem is the warning it's giving me for the final leg (Mannheim to Stuttgart). It says:
Current information about your connection:
IC 2019: Mannheim Hbf->Stuttgart Hbf: Construction work. This train will arrive 20 minutes late.

I'm not particularly concerned with arriving in Stuttgart late. I don't, however, have any clue what "Hint: Station passed through multiple times" means. Is that because I set the connection/stopover time in Heidelberg to eight hours?

There's a six minute transfer at Mannheim. If the incoming train is technically on time but I'm too slow to get on the one headed for Heidelberg, what exactly happens? There appear to be several trains per hour between Mannheim and Heidelberg. Is missing the connection no big deal or will I be charged some fee/forced to purchase a separate VRN ticket? By the way, the honeycomb tariff systems for all these different German states couldn't be more confusing.

I'm currently going through all these different long-distance trips I know I have to take, attempting to plan out the cheapest routes. I want a decent estimate of total travel expenses, minus U-Bahn/S Bahn in the cities. If the cost difference between a pass and the tickets is less than €50, I'll probably just buy the pass for convenience's sake.

Yikes, I feel like Lee needs to weigh in here. I take trains all the time but this is like a math problem from a nightmare.

Right now there is massive construction going on around Stuttgart as part of the Stuttgart 21 project - Europe's largest public works project! If you're interested in how they're gonna move 18 km of track underground (plus the entire train station) the tower at Stuttgart's Hauptbahnhof explains it all in German and English! But you just wanna go where you're going to go.

My understanding is if a connection is missed due to delays on DB, regardless of your ticket, you're good on an alternate train to the same destination of the same class. So, if you miss a connection on a regional train, you can hop on the next one. If you miss a connection on an ICE to a delay, you can hop on the next ICE. I may not be correct but this is how I've traveled and how it's been explained to me. But if you cause the delay yourself on a sparpreis ticket, then you're out of luck and have to pay the full price for the next ticket.

Given the amount of crazy construction, any missed train due to delays shouldn't cost any extra. But I wouldn't want to be held to that in a court of German law. Hopefully other people can weigh in.

Stuttgart 21? I find massive public works projects fascinating, so I'll probably do some research on it.