{I'm writing this on an airplane as my fellow passengers find their seats. My company has a conference in Texas, so hi-ho, hi-ho, off to The Great Nation of Texas I go.}
Wowza, what a great question! I really love this - good job, Jen and Morgan!
Short answer, since I'm on a plane and got up at 3:30 this morning: I wouldn't date anyone that I couldn't see myself marrying. That doesn't mean that I wouldn't go on a date with someone unless I knew he was The One, but I wouldn't go out with him unless there was a possibility.
That being said, I think considering someone an "option" is different than considering that person The One. I think some NAS girls have mentioned Cindy's "3 Date Rule," and I really appreciate it (that is, if I'm thinking of the right rule!). Go out with a guy if he asks and you're interested, but don't start a relationship with him unless he is an actual option for a husband.
Personally, I feel pressure on myself to know my list of character qualities I'm looking for, because a guy can be really fun and awesome and interested, but if he lacks my non-negotiables, I couldn't enter into a relationship with him.