Looking for Itinerary suggestions

I count 8 full days (not including your flying in and flying out days) and you've already listed 6 destinations (including Munich)--some of which are separated by significant amounts of train travel time just to get from one place to another. For that reason, I suggest that you be cautious about adding still more destinations (as mentioned in your post).Here's a link to further tips on planning a Europe itinerary Are Your Travel Times So Long That You Won't Have Time to Do What You Went to Europe to Do?Hard copy maps in books don't convey the significant travel time required to get from Destination A to B to C, etc. These are significant in your case.From your post: "Any suggestions for a loop that makes sense and other towns along the way we shouldn't miss?"The itinerary locations you've listed so far don't lend themselves to an efficient circular loop, for this reason: you'll have to first go from Munich east (or reverse this route) to Salzburg, then farther southeast to Hallstatt, then way west to Neuschwanstein, then way southwest to Lauterbrunnen, then all the way back (northeast) to Munich. Here's an online rail schedule website Rail Schedules that will allow you to get an understanding of the schedules and of the station to station train times.You'll add to these station to station times the time needed to pack up and check out of your hotel every time you change locations, get to the train station, wait for the train, same drill on the arrival side that day. A rough rule of thumb is: every time you change sleeping location it takes a half day, and that's not including the station to station times.

Just so you know, your Eurail pass will only get you a 25% discount from Interlaken Ost into Lauterbrunnen. Same for any ride up either side of the valley. The whole area is not too Eurail friendly. It's not good on the bus system in the valley. If you have a real Swiss pass or card, which you can buy at any station, all fares are fully covered on the valid days except from Wengen to the Jungfraujoch (50%) and from Murren to the top of the Schilthorn (50%).

I know you're right... We were in the Lauterbrunnen valley 4 years ago and loved it so much. Is there anywhere else that is more reasonable distance-wise that is similar (hiking, cows, waterfalls, etc)? Maybe the Appenzell area?

Just go south to the Bavarian or Tyrolian Alps. Although the Lauterbrunnen Valley itself is unique, the mountains in southern Germany and western Austria are basically the same, scenery and activity-wise... but crucially, MUCH CHEAPER and more convenient for your trip.

Instead of the Berner Oberland, you might think about Oberstdorf and the Illertal in the Oberallgäu region of SW Bavaria. It's about 2½ hours by regional train (so you can use a Bayern-Ticket). Oberallgäu is a dairy region (Allgäuer cheese), so there are lots of cows. They graze them on the ski slopes in the summer.

Just outside of Oberstdorf is the Kleinwalsertal, which is a part of the Tirol, but isolated from it by the mountains. It's a good place for hiking.

There is a bus that leaves Oberstdorf just before 9 AM in the morning and goes to Hohenschwangau (Neuschwanstein). The bus back gets to Oberstdorf in the early evening. You'll have far more than enough time in Hohenschwangau to see one castle, maybe both. The first time I did this trip, we saw Neuschwanstein, then looked around shops in Hohenschwangau. The second time we saw Hohenschwangau castle and still had time to go into Füssen and look around there.

I can't remember any waterfalls in the area.

The Appenzell area is lovely but probably not as spectacular as the Lauterbrunnen valley. But what comes close to it (and yet is unique in its own way) is the Berchtesgaden area (www.berchtesgaden.de/en). Don't miss a boat ride on Lake Königssee to St. Bartholomew. It's all just across the border from Salzburg. I also second the idea of spending some time in Oberstdorf. What about Garmisch-Patenkirchen? They have a spectacular white water gorge (www.partnachklamm.eu) and the cable car ride up Mt. Zugspitze is also quite something.