For this game, I also strongly considered running it in GURPS, now that GURPS Dungeon Fantasy is out, but it occurred to me that a) I really, really like Ars Magica, and b) I haven't run it in a long, long while. The obvious question: "Why not run it in D&D 4E?" The answers boil down to "Because I didn't enjoy running my D&D 3E game enough to try that again sooner than a game I did really enjoy running." This is no doubt unfair to everyone involved, although kaynorr will be running a spot of D&D 4E this summer to slake everyone's battlemat-crazed thirst.
THE GRYPHONS OF CALYFERNE
Cadamosto returned to Portugal in 1456 with staggering news: He had discovered the island of Antilia, far to the west across the Atlantic Ocean. Better yet, he had heard of other islands, rich in spices, gold, and cities -- Hy-Brasil, Cibola, Estotiland, Norumbega -- and greatest of all, the legendary Calyferne, ruled by Amazons and guarded by gryphons! A chain of Indies stretches to the Kingdom of Prester John himself, and to the lands of the Great Cham of Asia, and you have a copy of Cadamosto's map and a ship that will take you west to find them. You are adventurers of the Order of the Golden Fleece; some learned in the wizardly arts, some practiced sailors or sell-swords, all willing to explore these new isles for Prince Henry the Navigator, and for treasures magical and mundane.
Do not be fooled by the cunning historical persiflage above! By old-school fantasy request, this game will feature: beautiful princesses, villainous pirates, aloof elves, clouds of black powder smoke, fearsome dragons, swarthy dwarves, enigmatic glowing gems, leering mandarin-viziers, heaps of gold, alabaster cities, hyena-headed gnolls, subterranean passages, sword-fighting, missing idols, magic rings, cruel giants, and the Mighty Kraken. Plus griffins and California, just like the title says.
System: Ars Magica 5th edition, with whatever tweaks Craig's extensive playtesting in his other campaign have proven necessary, without Houses or the Order.