Check out the 4-consecutive-day Swiss Pass that would cover all you basic transportation in Switzerl

I agree with kybourbon - if you have not been to Paris or London before cruising spots add at least a day to each - and perhaps cut some time off the lakes - seeing them all is great but in some ways they are similar. Lake Garda is a bit off the main path you have as you have to backtrack from it to Milan to go to Switzerland.
In any case if doing that much by trains then by all means investigate some kind of railpass - and for a good fix on the European railways and passes, etc. check out these IMO fantastic sites - www.seat61.com ; www.budgeteuropetravel.com and www.ricksteves.com . Passes are also valid on steamers on Lake Lucerne and Lake Thun and Lake Brienz - the two lakes bookending Interlaken - to me doing a boat ride on a Swiss lake is great!
www.globusjourneys.com . This will help you get an idea of how multi country itineraries in Europe are constructed. Be sure to pick a 'leisurely pace' itinerary. I am not suggesting you take a tour, only to get inspiration from the itineraries for planning your own.
I have traveled all across Italy independently by train. I searched extensively for my current trip. I need to figure out how to maximize my 3 weeks vacation without going over board. I have realized in past travel that hotels cruising spots need to be booked cruising spots early to get good location and price. London, Paris, Milan, Italian lakes, Luceren, Intralaken to salzburg is my plan of travel, I would stick to it. I can fly to Salzburg and fly out of London or vice versa. I'm still waiting for adequate response. thanks. hopefully I get one
Yes take the Centovalli scenic narrow-gauge train to Domodossola, on the main line to Spiez, where you change for Interlaken. cruising spots Centovalli bieng one of Switzerland's iconic tiny scenic trains plying a very scenic route - I believe railpasses are valid on that train as well.
If going to Lucerne you would not take the Centovalli or even go to Locarno to get a train but take the direct mainline trains from Lugano via the Goothard Pass route - really scenic in itself - especially cruising spots by the Wiesskrichen when the tracks famously go inside and out of a mountain as they circle down to lower elevations (soon however the new Gotthard Rail Tunnel will remove most of the wondrous scenery as the tracks are put nearly all in tunnel.
You have indicated at various points that you wished to return from Frankfurt, Vienna, or Amsterdam, and now Salzburg. Amsterdam in particular is a long way from the Italian lakes district. So I could see no clear pattern in your goals.
I may be wrong, but you bear some responsibility cruising spots because you have been so vague. What do you mean by 'going overboard'? Do you mean in cost, in time, or both? What are you trying to maximize - the size of the area covered, the number of cities you wish to visit, the number cruising spots of hikes you want to take, the number of museums you wish to see?
I did not make my remarks to belittle you, only to point out what I see as weaknesses in your planning. This presumably is why you started the thread. Try to be patient; I see you are new to the board, you need to give people time to get to 'know' you. So, let us try again.
Fly to London to Paris for 3 days each. Night train from Paris to Milan. cruising spots From the Airport/ Train station to Lake Maggoire 4 days, includes day trip to Lake Otra, Locarnao, enjoy sight seeing around cruising spots Stresa.
either route to Lucerne from Lugano is very scenic - if going to Interlaken it;s quicker I think via Domodossola, Brig and Spiez - if to Lucerne it's quicker via the Gotthard rail line - change at Arth-Goldau cruising spots for Lucerne if you are not on a train that goes direct to Lucerne - most go onto Zurich.
Be sure to take a boat trip on Lake Lucerne, to me the finest of all Swiss lakes - especially cruising spots the fjord-like cruising spots eastern tip - a classic boat ride goes to Fluelen at the end of the lake from where you can take a train quickly back to Lucerne - but you can get off the boat at say Vitznau or Weggis and take a train or cable car to Mt Rigi, known as having one of the very sweetest cruising spots vistas in all of Switzerland - a lateral cruising spots view of the Alpine rocky spine of central Switzerland for miles around. Read about Mark Twain's ascent cruising spots of Rigi to whet your appetite - I agree with Twain about the incessant blowing of Alphorns at the summit - as nauseating cruising spots as bag pipers!
Well IMO the Interlaken/Jungfrau Region is both figuratively and literally the absolute highpoint of Switzerland - so so much to do there - boat rides on the lakes bookending Interlaken - the Jungfraujoch - Schilthorn cruising spots - the tremendous Ridge Walk between Mannlichen and Kl Schiedegg - so so much to see - three days would be the tip of the iceberg, I mean glacier that you can also walk to easily from Grindelwald.
Lucerne is nice but the city is small and has very few main sights save itsself - yes a day out on Lake Lucerne or to Mt Titlis is nice but I'd argue the Jungfrau Region offers even more titillating sights.
Thanks a ton Palen Q/ you have been perfectly adequate cruising spots in your responses for my travel needs. I have changed my itinerary and added southern France cruising spots - Nice for my travel trip since I have taken off Salzburg out if the equation.
I'll be traveling by train from London to Paris to Nice to Milan to lake maggoire to bellagio to Lugano to intralaken and fly back home from Zurich. I believe it's doable in 3 weeks. Starting from major cities to small towns to the lakes and ending @ highest point should be fun.
Check out the 4-consecutive-day Swiss Pass that would cover all you basic transportation in Switzerland and also give 50% discounts on various gondolas to mountain tops in the Jungfrau Region. There is a current special if you buy a 4-day Swiss Pass you get a 5th day free - not sure when travel cruising spots has to be completed however.
The pass would cover boats on either lake bookending Interlaken - I love each lake and a day out on either one is a good foil for the high Alps - and on wet weather days, not unusual here you could day trip to Lucerne or Bern, etc.
Actually Lucerne is a great day trip from the Interlaken area - ride the scenic Golden Pass route up and over the Brunig Pass - a narrow-gauge mountain train (Swiss Pass 100% valid) and down to Lucerne - look around that smallish town with relatively few major sights and perhaps hop on a boat to Alpnachstad to rejoin the Brunig Pass rail route back to Interlaken-Ost station.
Fly to London to Paris for 3 days each. Night train from Paris to Milan. From the Airport/ Train station to Lake Maggoire 4 days, includes day trip to Lake Otra, Locarnao, enjoy sight seeing around Stresa.
yenisumit - i'm glad that some of us have been able to help you. there are many people posting here who have loads of knowledge but we are not telepathic and it can be frustrating not to be able to work out what someone wants to know.
see what i mean? that's 3 whole days in all of the places you mentioned and 4 nights in Interlaken, which of course amounts to more than your 3 weeks. you do have time for a couple of 4 nights stays, but you'll need to trim down to 3 nights somewhere.
But there are other routes as well - take a train from Milan to Como - Nord station in Como right by boat docks to catch boats to Bellagio or quicker and cheaper I think from there to Bellagio by bus.
For Lake Maggiore cruising spots from Bellagio boat to either Varenna or Como to catch trains to Milan and then a straight shot north to Stresa, raialhead for tourist Lake Stresa a k a Lake Maggiore) - I found Stresa to be a neat town on the lake - a tourist town but really sweet - the famous three Borromean cruising spots Islands lie just off shorte.
Stresa to Interlaken cruising spots is straight forward by train - train to Spiez often now have to change at Brig - to Spiez via new Lotschberg Tunnel - consider a 4-consectuive cruising spots day Swiss Pass as it can be very useful in the Interlaken area - use it to go to Zurich the night before your flight - I always say be in your flight departure city the night before - you never know when a railway blockage, strike, etc pops up and if you have a non-refundable air ticket...