Surprising in a world of Jerkass Gods and excessive heroes, but one actually exists in Classical Myth with the story of Baucis and Philemon: after being the only people in their village to grant a disguised Zeus and Hermes the Sacred Hospitality despite their poverty, they are granted a wish for doing so. They wish to die at the same moment so that they would never be widowed. As if that wasn't enough, Zeus throws them something extra: when they do die, they are turned into trees with branches entwined forever to symbolize their love.
There's actually a fair few in between the usual bloodshed and weirdness. After all, at least some of those stories gotta have a Happy Ending, and the gods do Pet the Dog at times.
Psyche, after enduring all manner of trials (while pregnant) to gain back her husband, Cupid, not only wins over Aphrodite's tasks, but is taken to Olympus to live with Cupid forever, and their daughter is named Delight.
A rather odd one, thus fitting for Hermes: When Pan was born, his own mother ran away in fright due to Pan's lower half being that of a goat's. Hermes' reaction? He thought Pan looked awesome and took him to Olympus to show him off.
When Penelope and Odysseus embrace after ten years of his absence, it's described in terms of an exhausted swimmer who comes crawling back onto the warm shore, "in joy, in joy, leaving the abyss behind."
The fact that Odysseus loved Penelope (who is already getting old) so much that he chose her over immortality and a goddess for a wife.
Galinthias. Faithful friend of Alcmene, Heracles' mother, when Hera got Eilithyia (goddess of childbirth) to delay Heracles' birth, Galinthias tricked her into stopping before Alcmene was driven mad by the pain. Gods being gods, she was turned into a polecat, and then Hecate came along and adopted her as one of her animals. Sometimes even the Greek gods do random acts of kindness...
Many versions of Hades and Persephone's story. In particular, there's the fact that Hades was probably the only Olympian who has never, ever cheated on his wife; the one time he came close to it, it was because the girl was trying to seduce him!And then Persephone came...
After Ariadne was killed by Perseus, Dionysus descended to the Underworld to bring her and his mother, Semele, back from the dead and made them both immortal.
While far from perfect, Perseus was amng the closest to a Nice Guy among the usually prideful heroes and semi-gods. He went "Medusa hunting" not for glory or wealth, but to save his beloved mother Danae from her Stalker with a Crush who happened to be the king of the island they lived in. And when he punished said stalker via petrifying him as well as his court, instead of taking the throne for himself, he gave it to the fisherman who helped him and his mom — who happened to be the rightful king, dethroned by his brother aka the evil king.