It seems since Starlight (which I thought was awesome until I saw Starlight was ripped from XI), the whole land of Ezorea has been in a constant state of celabration. Personally I am fine with having a few world wide events:

Starlight - Around christmas I loved the music and the look of the cities, best event so far in my opinion.

Valentines day - The event seemed a bit poor, but the real event is a bit poor too in my opinion.

Easter - I have not really tried this one, but I am happy for it to be a world wide event.

Now, each city we currently inhabit respresents a city-state, and I feel they should each have a unique event to that state. After all does Japan have the same events as the UK, or US? For example, I feel Heartstrum, should have been a unique event to the city with the samurai guild (if they introduce that class). Ladies day could have easily been a Japanese spring festival event and localised to say Gridania, because of the cities connection to the great forest.

Those though are just examples for the ones which already exist. You could further this idea, by giving events a specific disciple for which the event is based. For example, Uldah is said to be a trade city, so having an event for DoH specifically has its unique event.

In conclusion I would like to see the ideas of events expanded on naturally. Some of them felt half finished, Ladies day was my number one example for this. They Cherry Blossom trees looked good, but the confetti did nothing. I also firmly believe cities should have their own events, it may move players around the map, but mostly it would make it feel like each city-state, is its own state with its own identity.