Reasons for Dating
I would like to be in a relationship again. I've had some really great long-term relationships that have been emotionally satisfying in ways casual dating can never be. Also, bluntly: I hope, at some point, to find someone to share the rest of my life with.
That said: you don't know if someone is a person you'd want to seriously date until you've gotten to know them... while dating. I'm pretty adventurous, though, and if someone asks for my number and seems nominally my type*, I usually give it out. You never know.
I think that the key is to be clear about what you're looking for. I'm not going to tell someone on the first date that I'm looking for a serious relationship, but after awhile, if things progress to a certain point it should be fairly clear. Communication is key, as is not deluding yourself. We've all had (or been) the friend who kept seeing someone who was clearly just in it for fun, but they have their heart completely invested, right? That person didn't read any of the signs, nor did they ask any questions.
*I don't really have a type, although they are very smart, social, have great senses of humor, know who they are, but don't take themselves too seriously. Outside of that- all over the place. From musicians to military intelligence, I've crossed the spectrum.