Again, I arrive at threads too late, so I can't post on the thread itself (it's over 20 days old)
So here's my contribution to the "Mood Music" thread
I'm kind of a music snob, but if it was me in that situation (which is rarely is right now, but it'll change) I prefer instrumental stuff. I dunno, words can get in the way sometimes in my opinion.
Here's some "moody" type of music, but it all depends on the mood you want to set. These are on youtube or downloadable so here goes (these are instrumental):
Osmosis by Liquid Tension Experiment (honestly, I could loop this and just listen to it all the time)
Stillness by Jordan Rudess
Ending Credits by Opeth
Hang 11 by John Petrucci and Jordan Rudess (off the album: An Evening With)
Indian Summer by Steve Morse
Requiem for a Dream Theme by The Kronos Quartet (cool movie too, but not the least bit romantic)
Lost Without You by John Petrucci
Always With Me, Always With You by Joe Satriani
Hourglass by Liquid Tension Experiment
Tippi Toes by The Meters
Stories to Tell by Stanley Clarke (kinda porno sounding, heh)
Always and Forever by Pat Metheny
Tidal Convergence by Ozric Tentacles
Hell's Kitchen by Dream Theater
White Wash by Buckethead (This is probably one of the most romantic songs I've ever heard)
Too Many Humans by Buckethead
That was just some stuff that's instrumental that gives you an idea, here's some stuff that have words and all that good stuff:
The Way by Jill Scott
You Got Me by Jill Scott & The Roots (check out Dave Chappelle's Block Party movie to see this song performed, it's awesome)
Love Will Find a Way by Yes
This World by Zero 7 (the one on youtube has crappy quality though)
Asilos Magdalena by The Mars Volta (if you have a girl who can speak spanish, she might be impressed by your choice here)
Every Breath You Take by The Police (ironically this song is about a stalker but they won the grammy for best love song, and then told everybody it was about a stalker and how retarded everybody was for thinking otherwise

)
Baby You Got Me by The Roots featuring Erykah Badu
Lady by Styx
June by Spock's Beard
Suite Madame Blue by Styx
Mr. Bombastic by Shaggy
Anything by Queen (no there is no song called "anything" by queen

) will get her in -some- mood (everybody loves Queen!)
The Great Gig in the Sky by Pink Floyd (I know there's vocals but no words, so I guess this could be in -both- categories)
Darkside of the Moon by Pink Floyd because if she doesn't like Pink Floyd you might as well ditch her now.
In Your Eyes by Peter Gabriel (you can thank that movie "Say Anything" for that choice, but it is a great song none the less)
Not Just Knee Deep by Parliament Funkadelic
No More Tears by Ozzy Osbourne (get that whole porn-rock feel)
To Bid You Farewell by Opeth (has both slow parts and rocking parts)
Ride With Me by Nelly
Angel by Massive Attack (you'll recognize this if you saw the movie Snatch)
Ten Years Gone by Led Zeppelin
Make Me Bad by Korn (this is a definite maybe, depends on the girl I'd say)
One Time by King Crimson
White Rabbit by Jefferson Airplane (probably best if you're stoned though, heh)
Big Pimpin' by Jay-Z
Seven Days in Sunny June by Jamiroquai
Virtual Insanity by Jamiroquai
You Give Me Something by Jamiroquai
The Payback by James Brown
I Got Ants in My Pants by James Brown (If you've seen 40 Year Virgin, you know this song)
Summer Romance by Incubus
Stellar by Incubus
Crazy on You by Heart
Serenity by Godsmack (another maybe, cool song, but may depend on the chick/mood)
In the Air Tonight by Genesis
Let Go by Frou Frou
Misunderstood by Dream Theater (starts off slow and soft and then kicks your ass metal style)
A Smaller God by Darling Violetta
Mexico by Cake
Letting the Cable Sleep by Bush
Passive by A Perfect Circle (another maybe)
Lovesong by 311 (or the Cure, I kinda like the cover by 311 though)
In my opinion this is all subject to your own opinions and you should use what you like or what feels right at the time. I think the best stuff is heavy in the lower range (bass, drums, piano) and has more of a smooth bass line and no screaming/yelling. Also, slower tempos are probably the best, but it depends what kind of mood you two are in

.
I'll post more as they come up.