I'm sort of like HollyBlue, but without the submissive aspect. I remember daydreaming about the "big guys" from the age of 12. Yes, I had been told the "size doesn't matter" stuff, but I thought it was logical that it would matter. (although I do think this varies from woman to woman...)
I didn't verbalize any of this fantasy, really. Just thought it, and my fantasies are more in images and phantom-tactile (yes, I actually "knew" what sex was going to feel like before I actually had sex, just from imagining what it would feel like!)....
Then, in 1986, I read a book that contained the verbal version of MY sexual fantasy:
The Valley of Horses by Jean Auel. Truly one of The Books That Changed My Life! My only sexual experience up to this point was with one guy (in 1984), who was medium or maybe a little on the small side. So while I still fantasized about being with a big guy, I didn't know exactly if I would be ok with that (although I was pretty sure I would be, being the phantom-tactile fantasizer that I am).
Later on, I had a couple of partners in the 7' to 7.5" range for length and 5.5" to 6" range for girth. Definitely a different feeling from the other guys, and no problems with being "too big" at all. In fact, I talked extensively to one of them, and he said that I still had room!

Apparently my physiology is made for a big guy. It isn't something that anyone is able to tell, and my body type is not the type that most men go for, so my experiences have been rather limited. No guy has ever "bottomed out" in me, for instance. I have no idea what that would be like, or what size he would have to be for that to happen.