OP, it is an interesting question, but I think you are coming from a somewhat wrong perspective. What you have essentially done is constructed an optimization problem based on limiting constraints -- x number of places that need to be visited, limited number vacation slots a year, and expiry dates of locations based on your increasing age.
First, you have to accept that if indeed you have limited vacations and you are not willing or able to get more time off somehow, you simply might not able to do it. BUT even if it is possible to solve the optimization problem so that you can hit up all the places you listed under suitable age conditions, it doesn't mean it's a good idea - because the problem you are solving - "completeness" - isn't necessarily a valuable thing to achieve.
For example, what if right now at the age of 25, you really want to go to Eastern Europe for whatever reason. But your 'calculation' tells you that you have to wait until you are 35 to go there in order to optimize. Does that mean you should wait 10 years before going? I would argue: of course not. If you want to hit up some specific place on your next vacation for whatever reason, just do that. By the time you are 35, you might not even want to go there anymore, or be in a committed relationship, or whatever. The place itself, as Enigma noted, could have changed significantly by then too. And as Rio pointed out, just because it's doable, doesn't mean you'll be able to do what you could have done at a younger age.
Another example, what if you go to Ibiza at 26 and love it and want to come back when youre 27 and 28, but your age calculation tells you that you must now do spring break and something else instead. Should you not go where you want to go at the present time because of some completeness plan you made years ago? Again, hardly seems like a good idea.
For a basic guideline, before you're 30, hit up some party spots that most appeal to you, like some of the ones others have mentioned. But beyond that, don't worry too much about it or treat it as dogma. Just go to the place you feel like going to most at the time...your top preferred places will likely change every couple years anyway.
First, you have to accept that if indeed you have limited vacations and you are not willing or able to get more time off somehow, you simply might not able to do it. BUT even if it is possible to solve the optimization problem so that you can hit up all the places you listed under suitable age conditions, it doesn't mean it's a good idea - because the problem you are solving - "completeness" - isn't necessarily a valuable thing to achieve.
For example, what if right now at the age of 25, you really want to go to Eastern Europe for whatever reason. But your 'calculation' tells you that you have to wait until you are 35 to go there in order to optimize. Does that mean you should wait 10 years before going? I would argue: of course not. If you want to hit up some specific place on your next vacation for whatever reason, just do that. By the time you are 35, you might not even want to go there anymore, or be in a committed relationship, or whatever. The place itself, as Enigma noted, could have changed significantly by then too. And as Rio pointed out, just because it's doable, doesn't mean you'll be able to do what you could have done at a younger age.
Another example, what if you go to Ibiza at 26 and love it and want to come back when youre 27 and 28, but your age calculation tells you that you must now do spring break and something else instead. Should you not go where you want to go at the present time because of some completeness plan you made years ago? Again, hardly seems like a good idea.
For a basic guideline, before you're 30, hit up some party spots that most appeal to you, like some of the ones others have mentioned. But beyond that, don't worry too much about it or treat it as dogma. Just go to the place you feel like going to most at the time...your top preferred places will likely change every couple years anyway.