I'm trying to decide between several destinations for a 4-day trip in September in Europe

This is a 4 day trip in mid/end September mainly for architecture and monument. I wouldn't visit a lot of museums, just a few.

Here are the destinations I've put on my list. I also wrote what are my fears :

Architecture and monuments :

- Vilnius + Kaunas (I checked pictures on Google, both look good/very good but they seemed less appealing than Tallinn for example)

- Riga and/or Tallinn (4 days in Riga might be too much ; same for Tallinn ; travelling between the two cities is annoying because I lose half a day and it costs more money)

- Tbilisi (not easy to get there from where I live)

- Kutaisi (is there enough to do in 4 days ? is there a good amount of architecture and monuments ?)

- Baku (it would be during the week of the Formula 1 GP so I'm afraid that there would be too many tourists, hotel prices would be very expensive, roads closed...)

- Bucharest + Brasov (I feel like Bucharest is harder to like than other destinations based on what I read on reddit ; this is just a feeling of course)

- Jersey + Guernsey (+ Alderney ?)

I also would love to visit Faroe Islands even if it is not a destination for architecture or monuments (4 days might be too short ; how is the weather in september ?)

Which one would you recommend me if you had to choose ?

If you have other suggestions you can write them. (I already visited Budapest, Slovenia, Malta)

Thank you in advance