I would say I'm as sure as I can be without asking her out that she's interested. She doesn't shy away from me touching her or her touching me longer than necessary, we tease each other a lot in a playful way, I've given her a nickname/pet name that only I call her, and she seems to make sure I don't get to much alone time with other ladies.
Anyway, I plan on being direct and to the point, and tell her I want her and we're going out. I'm pretty sure she'll say yes, but if for some reason she doesn't what's a good response to keep out friendship from becoming awkward? The rejection doesn't bother me, but I'm not sure what to say if she says no and I don't want to end up saying something dumb like "oh... ok... bye" if she says no.