Valindor is one of those NPCs. I know he doesn't say much, but I always felt compelled (especially when I started playing Gwaihen) to take him away from Riften to see the world like he always wanted to. I get the impression that he's stuck in Riften due to some kind of scam pulled by the Thieves Guild (could be as simple as losing a game of cards) that has him up to his ears in debt. He can't pay it off, but hey, that's okay, so long as he works his bones away at the Fishery. He lives in a tiny hole in the wall, down on the lower section of the canal, where you know the water is about as filthy as Bravil's canal, right across from The Ratway where the Thieves Guild can keep an eye on him. But he's not included in their activities. Oh no. Isolated and left to work on boats or haul in fish, the failed apprentice of a master armorer, he possesses none of the skills useful for a life of thievery. I imagine a great deal of bitterness regarding the Riften locals, though his Bosmeri attitude of "living in the moment" never seems to aid him in planning his away out of his financial situation or even leaving Riften and covering his tracks.
Ah, but I digress. Valindor in my story is not quite like the Valindor I've described above. A pity. Nevertheless, he's now Gwaihen's companion, at least (yay console commands), and perhaps they'll be married.
Lynly Star-Sung has a sexy accent, looks pretty attractive, and will play you a very nice song on her lute if your Speech is high enough. She's the only reason why my characters would ever willingly sleep in that Inn, it's otherwise terrible. It's a shame about her quest though. I agree with Jacob that she would have been a great Marriage candidate.
A lot of people apparently like Sapphire as well. Personally I think she's okay, the main problem being most of my characters won't touch Riften with a ten-foot pole. That's including my thieves.
Hmm...this is actually a tough one. I've only married two people in Skyrim on two of my characters, Aela on my main and Camilla on my very first character. Looking over the game I wish there were a few more options but beggars can't be choosers. So here's my 3 choices going from most realistic to least realistic.
1) Ysolda - She's a girl with ambition to become good at trading, which in Skyrim is useful. Though learning trade from the Khajiits is about all she is doing in-game. Adding in the fact she's a redhead too...just sayin'.
2) Serana - Excuse me while I say some really generic stuff about her. Serana has quite a bit more detail put into her character than any other female in Skyrim (imo). From the time you save her till the fight with her father you can feel a friendship being made. Unlike the other females in the game Serana will talk to you in a more "real" way. Granted of course her dialogue is limited like any other character. Combine her looks, skills, and realism she is one heck of a marriage candidate.
3) Alice - This is one of my made up characters so...yea, kinda impossible. I just through this in as a point that if custom NPCs/Marriage partners were possible (I guess they are on PC) I would have Alice. This character of course would be based off the Alice from the American McGee series. I don't know...I have a thing for emo girls...slightly sad, pale(ish) skin, black hair...*drools*