Special Days - Possible Calendar?
http://wiki.guildwars2.com/wiki/Mouvelian_calendar
This is the calender used by humans in Tyria, and it appears to have been adopted by the other races. The only annual holidays it recognizes, to our knowledge anyway, are Wintersday (the New Year, between the seasons of the Colossus and Zephyr) and Halloween, the exact date of which is uncertain but most likely occurring in either the season of the Scion or Colossus.
The Canthans and Elonians also have their own calender- http://wiki.guildwars.com/wiki/Canthan_calendar and http://wiki.guildwars.com/wiki/Dynastic_Reckoning- and from a RP perspective, humans descended from those peoples might measure time by those. The Elonian calender is little different from the Mouvelian, starting 200 years earlier and switching a couple of the seasons’ elements, but celebrating the same holidays with the addition of the Festival of Lyss, believed to occur in the Season of the Zephyr. The Canthan calender, on the other hand, starts 510 years before the Mouvelian, has months and ages as well as seasons, tracks years by a system like the Chinese zodiac (Year of the Rat, Year of the Pig, etc.) and celebrates neither Wintersday nor Halloween but has instead Canthan New Year (either at the same time as or a couple months after Wintersday) and the Dragon Festival in the Season of the Phoenix. Neither of these alternative calenders seem to have been adopted among non-humans.
As for the other races, they don’t have any known annual holidays. The charr and the asura as a whole are not particularly festive (with the exception of the Charr’s Meatoberfest, which seems to be a perpetual celebration to keep the soldier’s spirits up, rather than in memory of any event in particular), the norn need no silly dates to give them an excuse to celebrate (with the exception of the Great Hunt, which happens once every year on an unknown date), and the sylvari are too new and experience their history in too different a way to have anything to commemorate. Perhaps for these reasons, calenders seem to be a specifically human invention. Each race, however, seems to have taken to celebrating the festivities of the human holiday of Wintersday without adopting the reason the human’s celebrate.
Of course, special days like your example of the Queen’s coronation are likely to be celebrated, but those would be a one-off thing, not celebrated year after year after year. There’s also a perpetual carnival in Divinity’s Reach, founded and funded by the ministry to help the common folk forget their problems, and to stir up popular support for said ministry.
As for the lore behind the human holidays:
Wintersday: This was celebrating a battle between Dwayna and Grenth to influence the season, Grenth wanting a dark and somber time of reflection, Dwayna wanting a merry and festive celebration. This battle played out on Tyria as snowball fights between each god’s mortal adherents, and more traditional war between their immortal followers, Dwayna’s snowmen and Grenth’s grentchs. Probably due to the withdrawal of the gods, these events no longer take place, and the non-human celebrators do not embrace the religious aspect.
Halloween: This is the only time of the year Mad King Thorn and his servants can return to Tyria. The time leading up to this day has long been marked by paranormal disturbances, but these seem to have ceased for a long stretch of time before Guild Wars 2, so until this Halloween past most believed Thorn to be a myth (the asura apparently referred to him as the Great Bookah.)
Canthan New Year: Celebrates the new year, and the ascendency of a new celestial animal, who appeared at Shing Jea Monastery to partake in a feast in its honor. The apparition will not occur in Tyria, but it may still happen in Cantha.
Dragon Festival: Celebrates the Jade Wind, or more accurately, the Jade Wind’s failure to break the spirit of Cantha. It was celebrated through several unique competitions and a re-enactment of a repulsed invasion of demons during the Dragon Festival of 1585 CC.
Sorry about the long post, and enjoy your RP!
Halloween has more lore than what Aaron said, though not much. Basically, it’s a day in which spirits still within Tyria are more easily able to interact with the living. Humans also call it Mag King’s Day ever since Thorn began returning.
I don’t really got much else to add to Aaron’s post. There are other more minor human festivals (like the Festival of Lyss, though that was native to Vabbi, or the Convocation, though native to Luxons).
The norn don’t seem to hold annual holidays, except for the Great Hunt, which is basically a giant moot (aka norn party). The charr’s only known holiday is Meatoberfest (which one can witness in Diessa Plateau). Asura now have the annual Snaff Prize but that’s more of a competition than holiday. Sylvari don’t seem to hold any holidays.
Stop treating GW2 as a single story. Each Season and expansion should be their own story.