Itinerary...got one!! Love to hear from you, is it doable

Three nights in a place is only two days, and there is much more to do and see in Madrid, Barcelona, and Rome than you can reasonably do in two days. I don't see how you have time for a day trip to Siena or Toledo, since that leaves you only a single day in Madrid and Florence. Keep in mind that every time you change locations you will lose one half to one full day for travel and associated time-wasters (packing, checking out, finding your new hotel, checking in, meals, etc.). And then you want to spend time in Austria and/or Switzerland, with suggestions for places to see in Germany en route to Amsterdam? I only count five unallotted nights as it is, without adding Austria, Switzerland or Germany. In my opinion, you should scrap any thoughts of seeing those, and allocate your other five nights between Barcelona, Rome, Florence, and Madrid.

Agree with Nancy. Planning way too many cities in such a short period of time. I spent 8 days just in Barcelona last year and didn't see all that was on my wish list. If you only want to get quick visits and views (hey I rode by the COLOSSEUM in Rome and got this great picture) then it is doable. If you really want to experience Europe then I suggest focusing on a certain area and enjoy it fully. You mentioned family in Amsterdam. I would suggest a week in London followed by a week in Paris then end in Amsterdam. These 3 cities are easily accessible by train, allow for enough time to visit the major sights and a few day trips. Enjoy your trip no matter what you decide. Europe is awesome!!

Nancy is right, this is a very rushed schedule. I would add that 2 nights ie 1 day in Venice in peak season with all its accompanying queues is a pointless waste of time and money. Sorry. Most of your destinations are going to be hot.

Scrap your day trips or increase the time you spend in each city. You don't have time for Amsterdam and it doesn't sit well geographically with your other destinations. You don't have time for Australia and Switzerland either if you want to spend more time visiting places rather than in transit between locations.

Flights within Europe have been available for months and prices only head in one direction. Pin down your schedule and book asap.

You are travelling in school holidays, so you need to book your accommodation soon too.

I also agree with Jennifer. You are from the South so you understand the heat and humidity so I believe you can deal with it. However I still advise limiting your trip to a certain area. What about flying into Barcelona spending 5 nights/ 4 days with a day trip somewhere and then fly to Italy and spend time the remaining time there? I suggest Barcelona to Venice. Venice to Florence and Florence to Rome. Fly home from Rome.

You have 5 nights to fill in ...

Madrid 3 nights (day trip to Toledo)
Barcelona 3 nights
Fly from Barcelona to Rome
Rome 3 nights
Florence 3 nights (day trip to Siena)
Venice 2 nights
Milan 1 night
Swiss Alps (Lauterbrunnen) 2 nights
Rhine (Boppard) 2 nights
Amsterdam 3 nights

I would say 3 nights minimum in any small or medium size city, and minimum 4 nights in any large city. You will cheat yourself to do less than that IMHO.

Ideally, in a perfect world, more time would enable you to enjoy your journey languidly at leisure. However, time constraints prevent this, so do as much as you feel comfortable with and at a reasonable pace. Be satisfied taking in the highlights rather than every single sight along the way.