To continue with the pop songstresses, I think some candidates are Janet Jackson. Lady Gaga, Lily Allen, Kesha and Christina Aguilera.
*Janet Jackson said in an interview that she would fake a headache "if the guy wasn't packing"
*In an interview I saw on youtube (but couldn't find now) Lady Gaga was asked what she looked for in a man and she just said "A big dick." (To me it kinda came across as a joke, but who knows..)
*In another interview I saw on youtube with Lily Allen (that I couldn't find anymore either) she was asked what kind of guys have a chance with her and she said "Men with big penises". There are also several clips on youtube of her dissing small dicks in between songs at concerts. (With Lily Allen, to me it comes across as a sort of "edgy" image thing, although that doesn't mean she can't be an actual size queen, too)
*Kesha talks about what she likes in this interview: A big bushy beard and a big dick: KE$HA: HELL ON WHEELS
*Aguilera has a couple of size related song lyrics, and seems to like to flaunt her husband's size. I read it was mentioned during her wedding, and in this Ellen interview, she does some serious hinting from around 4:00 in this clip: YouTube - Christina Aguilera on Ellen DeGeneres
Also, the one from TLC that has a reality show where she's looking for a man, said on the George Lopez Show that "It's the size of the boat. I want a yacht."