I have a few ideas for higher level events content, but we can't do this until almost everyone has at least 1 level 80 character just to be fair. I'm sure some can be adjusted to include characters of all levels.
Once a large number of us get to level 80 I think we should host a
Caravan to Orr event. Where we escort lowbies and anyone who doesn't have orr unlocked into that zone. This technically doesn't have to be a guild only event. We can reach out the community too by allowing more people access to that zone.
Ranger Pet Menagerie event. One whole day, we all make rangers and help everyone who has a ranger collect every ranger pet there is in the game. Than we can take a screenshot of every pet there is in game at the same time. It'll be like a petting zoo, except these animals can bite!
Underwater Flashbang. Just get a bunch of people with guardians together and just go do some underwater content to see how awful it can get.
Pickaxe Frontier. Orichalcum mining and T6 node expedition. Plain, boring, but helpful for those who don't have level 80 exotics yet. Orr final map clear can also be included in this event since there are no hearts to do.
I'm sure that I'm not the only person who has thought of these, but since you're asking for ideas I thought why not. You can also collect all of the suggestions and edit them into your original post so that it's all collected in 1 post rather than spread out in this thread. ^
I'll add to this thread if anything new comes up in my mind.