I think any one or many of these events would be great as long as they are wrapped around roleplay. I think that adds spice to the events. Then roleplayers can participate and still remain in character and don't have to join in the fun on alternate characters. It can spark other roleplays within the community. Take a look at some history. If you look at the Nostr'yl Quest in the early days they incompassed the roleplay community both good and evil to help with their activities and none of them were limited to roleplayers but used roleplayers to build the story line. It was a lot of fun for all.
Some suggestions for your list of ideas:
As always with me ROLEPLAY!
Invasion of some kind (please temper it to allow us roleplayers and newbees to survive once in a while, cuts down on frustration and fear)
PvP Ladder events (we have many roleplayers that do work on levels and they would enjoy something like this)
Massive Mobs in a small enclosed space (that can be real playing field evener)
Mental event (puzzles, riddles) (Awesome, build something into an event that everyone, young and old can figure out)
Competitions Fishing/darts/race (fantastic idea that can include newbees as well as old hands)
That's my 2 cents!