Critique of my Europe itinerary next year

The Ljubljana airport lies well north of the city and is pretty much the same distance from Bled as it is from central Ljubljana. I would pick up the rental car at the airport, head to Bled, and skip the first night in Ljubljana (unless you have a special reason for wanting to be in Ljubljana that night).

The Slovenians will tell you that Škocjan Caves is the place to see, not Postojna. You will pass very close to Škocjan going to and returning from Piran. Škocjan is nature with expansive caverns that are like something out of Lord of the Rings.

I'm not sure how you plan to get to Scandinavia, but it looks like there are non-stop flights from Ljubljana to Copenhagen 4 days per week on Norwegian Airlines.

Interesting itinerary, but why combine places so far apart and then spend so little time in Scandinavia and Scotland?

Frankly, while I found Slovenia very nice, Scandinavia and Scotland exceeded my experience in Slovenia.

The Slovenians will tell you that Škocjan Caves is the place to see, not Postojna.

Thanks for the information

Interesting itinerary, but why combine places so far apart and then spend so little time in Scandinavia and Scotland?

Because for me, the best length to travel without getting burned out is between 3-4 weeks. I choose Slovenia to spend more than a week because Slovenia is underrated for now.

the initinery doesn't relate to the actual question! The question says you are flying in to Frankfurt, the itinery says Day 1 land Ljubljana, hire car, explore city. Highly unlikely, direct flights from Frankfurt to Ljubljana need a checkin probably too early from an inward intercontinental flight or an arrival in Ljubljana too late to do anything.

Day 12, leave hotel in Ljubljana and explore Stockholm. Ignoring the lack of direct flights, so a lot of the day will be lost at airports.

Day 16 leave hotel in Stockholm and explore Copenhagen. You'll have to leave early if you want to arrive before mid afternoon!

Day 20 leave hotel in Copenhagen and explore Edinburgh. No need to rush, there don't seem to be any morning flights, mid afternoon arrival is the earliest, the cheapest are mid evening arrivals.

and what happened to "the best length to travel without getting burned out is between 3-4 weeks" and "Germany as the last country I'm going to visit" ? 3½ weeks in and there's still no mention of Germany.