Please help fill my itinerary gap!

What do you have in mind? It's mostly Alps between the Interlaken area and Salzburg, so it would be mostly a variation of a similar theme. You would have to go a little further north into Germany for something different. Lindau on the Bodensee is a gorgeous little stop-over between the Berner Oberland and Munich, but it isn't the type of place where you would spend three nights (unless you had a car and used it as a base). Perhaps Chiemsee and nearby Rosenheim? Bad Tolz? Rail or car, as that would make a difference on what's feasible.

Thanks Tom.

I'm traveling by trains.

I was thinking of Innsbruck, but I don't know anything about the city.
Or a night in Chur after doing the Glacier Express then 2 nights in Fussen to see the Castles.

Have you been to Munich? If so, what did you think?

If I had to chose between two cities considering the rest of your itinerary, Munich and Innsbruck, Munich wins, hands down. Especially because you already have plenty of Alpine destinations on your schedule. Innsbruck's a decent city, but it's more of a place you visit as a quick stop-over, or as a base for further Alpine excursions. A bit industrial too. Munich, by contrast, is the capital of a former kingdom and a destination in and of itself.

That is the type of info I was looking for Tom, Thank you.
Thank you

Carrie:

Your planned itinerary is going to be extremely difficult to pull off in the order listed by train travel. I have traveled this region many times since 1970, and speak from experience.
My suggestions: Visit Paris and then fly into Venice (cheap) on EasyJet.com, a big budget airline. From there, take the train north thru the Brenner Pass into the Innsbruck/West Tyrol region. Spend a few days there rambling through the incredibly beautiful Austrian Alps, as it looks like Switzerland. Then catch the train up to Salzburg and eventually over to Hallstadt. You can easily go back west into Munich for the balance of your trip.
I'm talking about substituting Innsbruck for Switzerland, as it's right on the way to your ultimate destinations. Unless you have an important reason to go to Bled, Slovenia, take it off your itinerary. It is very much off the beaten path northeast of Udine and Trieste, and it's very, very difficult to get there. If you're looking for the mountain experiences, the above itinerary will do it so much cheaper and efficiently.
You're early enough where canceling prior hotel reservations shouldn't be a problem. If your airline reservations are made, you really should consider modifying your itinerary to meet your airline tickets.

Fussen & the castles are fantastic - I would trade time in Munich for them. Neuschwanstein Castle is not to be missed - all those awesome photos you'seen of it - it REALLY looks like that! Fussen is a charming town - do a little research on the various things to do in the area.

I was planning on taking the high speed train from Paris to Bern (4.5 hours) then local transport to Gimmelwald. 2-3 hours
Gimmelwald to Munich is 7 hours
Munich to Salzburg 2 hours
Salzburg to Hallstatt 2 hours
Hallstatt to Bled 7 hours
Bled to Venice is 6 hours.
I have been doing a lot of research. I didn’t think this itinerary seemed too hard but I am not an experienced traveler. Yes I have a couple of long travel days but I’m planning more where I want to see vs. easy places to see. Lake Bled is on the top of my list for places I want to go. I would take Munich and Salzburg out for Lake Bled if I needed too. I already have my flights booked to Paris & out of Venice.

Christi, do you think 3 nights in Fussen would be too many? I was planning on just a day trip from Munich but staying in Fussen sounds nice.

Based on your itinerary I am going to assume you are an outdoorsy person. Along with the castles there is an abbey and church, the town itself, fantastic hiking and mountain biking (rentals available), lakes to boat in and an alpine slide. Do a little googling about it - see what you think. It is nestled in a picturesque setting - the last stop on the romantic road.

Carrie:

I can tell you're very passionate about your trip, but your best view of Europe's going to be seeing the back of the train seat in front of you.

Lake Bled is just a little lake that's less than a mile wide and 358 acres in size. That's not a destination worthy of the time and effort it takes to get there. There are many, many more scenic lakes, like Lake Garda (NW of Verona) and the Lake Como region north of Milan that are truly special.
I think you're possibly underestimating Munich and Salzburg as world class cities in their own right.

I've also been to Fussen and Neuschwanstein, and didn't find it that appealing. After touring The Rhine, castles get to looking alike--especially fake castles of Crazy Ludwig.
There are just so many fantastic places you could easily visit with that time, especially since you'll be in Italy.

When I'm not sure of where to go, I try to look at the city's/area's official website. I also google images of cities and sometimes that makes the decision easier.

This is your trip, so if you don't mind spending a lot of time in transit, do it to get to a place that's important to you. I spent 19 hours on a bus to see the mosaics in Antakya, Turkey, and don't regret a minute of it. I'm sure if I posted that I will spend five nights in Rieti, Italy, I'd get responses that it's not worth that much time, but to me it is.

You are going to many sights that are my favorite! Yes, those really are long days of travel, we prefer 4 hours or less, but it is doable. You will blow a full day and lots of $$ with long travel, but i love your destinations so i think it is worth it. We have not done legs that long, and you may get really tired of trains, but on the other hand it is fun to look at all the scenery you have not seen before. Hallstatt is super small, you can walk one end to the other, strolling, in 30 minutes or less, if I remember correctly. I'm with you about seeing Lake Bled. It is on my list so we are going this summer. There is a lot to do besides look at the lake. We loved the Fussen area, but we just did castles so we stayed just 2 nights, beautiful around there. But everywhere you are going is beautiful, you'll love it ! Have a fabulous trip :- )