>>94653772I wanna say Tokyo but honestly I'd take her to the Pyramids then the Colosseum.
I think she'd also enjoy London for Baker Street. I don't know if she's into Holmes necessarily but I know Kudo's really into him and there's an arc where they visit London in Detective Conan so she might like it for that.
After that I'd like to take her to the Sydney Opera house for something because I know she likes the theatre too. Ideally I'd wanna take her to a musical too...
Then if I have time I'd take her to Osaka to see the Dearstage that's opening there and take her to Tokyo and take her to Sky Restaurant 634 and propose to her there.