[Missed Miss]

Penis size, like breast size, is usually more about visual impact than about functionality. That being said, women, I am told, can be quite sensitive to even quite modest changes in penis girth, reporting a greater feeling of fullness and, sometimes, more clitoral stimulation with a girthier partner. Changes in length is a different matter: a little deeper penetration is not noticed until the thrusting starts bumping up against the cervix, which most women find uncomfortable. With practice, and patience, some couples can learn to ease the glans of his penis past her cervix and enjoy full penetration, but that is more a matter of avoiding discomfort from a long penis than achieving more pleasure. One thing that a longer penis does offer is a great number of positions. Some positions are prone to the penis slipping out (standing positions or spooning for example) and a longer penis can give a couple more operational flexibility.
Of course, having too long, or too girthy, of a penis can also eliminate options as well if the penis in question is big enough to cause discomfort. This can be particularly true of oral or anal sex.
But the reason why most guys seem to want a big penis is so that other people will look at it and say "Wow, you have a really big penis!"

By the way, I love Diana Rigg (Emma Peel and Mrs. James Bond!)

Me, too!! She's GOREGEOUS!!
In the TS world, once they get the bottom half done, they use a series of plastic dildos which are called dilators. They use these to deepen their vagina and make sure that it doesn't close up on them. Seems to me (but maybe I'm wrong!), a GG can stretch herself out over time by having sex with a guy with a big one, or even just use a large dildo on herself they way TS's use the dilators. I've seen guys that have their urethra stretched WAY open over time, I even saw a guy put a real tampon in his!! So, if a guy can do this, what couldn't a woman with her vagina? It's just skin.