This may have already been suggested before, I don't know. But I have an idea of an event that you could run called The Big Lottery. The lottery would give players the chance to use a variety of currencies to purchase tickets for a lottery draw. There would be 3 lottery draws per day at a set time, and players would be credited with their winnings through the mail system.

There would be a tiered ticket system that would allow players of all levels and types to purchase some tickets and have a chance of winning something nice.

The currencies used would be:
Diamonds (from Marketplace)

to allow players to use up any loyalty / credits that they may have etc and allow them to purchase more if they wish to.

The tiered levels would be 1 - 5. Tier 1 being the most basic, through to tier 5 which could only be accessed by purchasing tickets at either tier 3 or 4 or a combination of both and winning a ticket for tier 5 for the next lottery draw. Tier 5 would have the best prizes.

The price per ticket could be something like:

Gold - 20 each
Gilda - 15 each
Loyalty - 10 each
Diamonds - 10 each

and players could purchase as many tickets at they like per draw, but there could perhaps be a limit on how many times a player can win a top prize at each tier, like say 5 times or something, to prevent the same people from winning all the time, and make it fairer for everyone.

Perhaps you could also implement some sort of ticket gifting system where players can purchases tickets for their friends, similar to how they can gift items in the marketplace.

The prizes could be something like:

Tier 1:
Everyday consumables
Quest synthesis materials grades 1 - 3 and scrolls grades 1 - 3
Simple lunastones / gems
Simple Gilda glider designs
Submarine Gilda designs
Gilda skateboard design
Tickets for the next draw

Top prizes for that tier:
A companion crust
A pack of 50 Gold
A pack of 20 Manastorm Crystals

Tier 2:
Lunastones / lunagems
Tempering materials
Hiram synthesis materials and scrolls for celestial and divine grades
Ship components
Gilda designs for items like the motorbike (sorry I can't remember what it's called), Farm wagons (the upgraded versions)
Tickets for the next draw

Top prizes for that tier:
A Battlepet (from the Marketplace)
A pack of 50 Gilda
A pack of 50 Manastorm crystals

Tier 3:
Rarer tempering materials
Rarer lunastones / gems etc
Hiram synthesis materials and scrolls for Epic grade
Dungeon items like Abyssal Shards etc
Tickets for the next draw

Top prizes for that tier:
A mount (from the Marketplace)
A pack of 100 Manastorm crystals
Rare lunagem / stone at a high level
A rare dungeon item (Perhaps a Mistsong portalstone or similar)

Tier 4:
Gilda designs (for items costing between 500 - 2500 in the marketplace)
Jewellery synthesis materials or high grade jewellery
Crest customisation items
Tickets for the next draw

Top prizes for that tier:
Either Gilda design for or an already built small ship / submarine / small house / glider
Pack of 150 Manastorm Crystals
Rarer battlepet
Rarer mount

Tier 5 Top Prizes:
(Can only be entered by purchasing tickets from tiers 3 or 4, and by winning a ticket for the next draw at tier 5)
Tickets for the next draw
Pack of 200 Manastorm crystals
Garden of the Gods items
Epic level weapons / armor or sythesis materials / scrolls
Larger ships / cars / homes such as the treehouses - either the Gilda Design or an already built item (if that's possible)
The rarest mounts and battlepets such as Zebras, Aquestrias, Fuschiafin, Black Arrow, Frost Dragon etc, and possibly some new mounts / battlepets that you'd make specifically for this event (hint hint )
Erenor Gear

Basically the best / most expensive things in the game will be at the final tier and the tickets for this tier will be bought with diamonds but at a much lower cost then what they'd be in the marketplace, as it's only a chance to win them, not a guarantee.