This is a good thread. It is very interesting to compare people's different strategies and budgets.
Good health, availability of time and money are all limited resources and in descending order of importance. Travel whenever you are able to do so.
I find planning a vacation to be the most interesting part of the process, figuring out where to go, more importantly, what time of the year and how long in each city. We find that 14+/- days to be a good length. Longer would be better but it's not so easy to take so much time off work.
Sept, Oct, Nov are great months to travel in Europe. It is the shoulder and start of low season, less expensive, less hot and less crowds. Also, the weather in Vancouver gets very rainy and dreary, so it is a nice time to get away on a vacation.
Ideally, we like to stay 5 to 7 nights in any particular city/hotel. Our minimum stay is usually three nights. One or two nights days are not enjoyable in my opinion. We end up spending too much time moving around, changing hotels, sitting in a train, etc and not enough in the city itself. Personally, I would not want to do three countries in 3 weeks.
Once we have a general idea of what we would like to do, the first big step is finding and booking the airfare. I like using Skyscanner and playing with the different combinations of departure and return dates. Selecting dates a few days earlier or later can make a huge difference in the price. We also prefer to fly open jaw so that we don't waste time doubling back or returning to a city for a wasted one night stay just to catch a plane home.
Once we have booked the airfare, we then book the accommodations. Booking.com, Expedia, Airbnb, VRBO are all great resources for checking out maps, locations, photos, prices, etc. However, wherever possible, we try to book directly with the hotel or property operator in order to save on fees.
As we book the accommodations, we also arrange how we will travel between the different cities, via train, plane, rental car, bus, etc.
The last step is figuring out things to see and do to fill our days in each city. We have a general idea, but usually, we decide what to one or two days before, keeping in mind that some attractions require booking in advance. This way, we can select things to do depending on our mood and the weather. We never get fussed about seeing everything because there is never enough time to do so.
We also never get to fussed about eating at a particular restaurant. If some highly recommended restaurant can be conveniently fit into our plans, we will eat there. However, we usually just find a place wherever we happen to be whenever we get hungry. A lot of times, we just open up Google maps and select a place that's within a 5-minute walk of where we are standing.
We did a two week trip to Spain in 2022 and a two week trip to Portugal in 2023. Our average daily cost (for all expenses including airfare, accommodations, meals, entertainment, etc) was less than €200 per person per day. In Spain, it was just the two of us and we stayed in 3 or 4 star hotels. In Portugal, we traveled with two other couples and we rented large three bedroom apartments in Porto, Lisbon and Lagos and rented a car for four nights in the Algarve.
With some careful planning, I think you can have a very nice 2 week European vacation for much less than $12,000. If you can do it for half that, you will have money to go on another 2-week vacation the following year.