Do you feel more women who elect to have BA surgery go with an above average size? If so why? I would think more women would want an average size or a size proportionate with their body. Would one go with an above average size to validate their femininity?

I think there may be slightly different factors for cis vs. trans here. 

I am personally built like a tank, but I don't want monster fake ta-tas to draw attention to myself.  Anything less than a "C" on me is too small and might draw things into question, so I'm thinking a "D" is just right on me for the correct proportion and "Goldilocks Zone".   

I would just prefer not to get stared at, have my gender questioned or get hit on by creeps.  If I end up needing one, I refuse to go to a doctor who needs to advertise.  The best ones in LA/BH don't because they are already booked for months. 

I just had my final meeting with my surgeon yesterday, and we picked out my implant size. He used some math that he explained, and it made a lot of sense. Measuring from the nipple to the edge of the ribcage is 1/2 the diameter of the required implant. If the nipples are centered, and the implant doesn't go all the way to the side, it will look like a half cantaloupe on a table. This math, given the wider male ribcage, will leave a gap between the boobs. He explained that a male torso would require a huge implant not to. The good news...wearing a bra pushes them together nicely.
I'm six feet even, with a 40" band size. We selected 620 c.c. round silicone implants. These should yield a D-cup. I told him I though a D was going to be too big, so we tried them on. They were just right for my torso, but would look very big on a five foot six, 130 lb. GG.
I picked my surgeon because he has done over 100 transgender BA's. We are different, and we need a surgeon who understands this. I like mine, and have put my money, and my trust in him.
Sept.9- the clock is ticking, and I can't wait.

I wanted a cup size that would look the most natural for my body; my doctor recommended 500cc silicone implants, which turned out to be D cup, and I am very happy with them.

I want enough to look unmistakeably feminine but not so much as to be a spectacle. I also don't like the look of boobs with overly huge implants - they don't have a natural look to me. I have a fairly large band size (a 40), so I'm thinking a large C or a small D would give me the look I want. Implants may be an option in the future if HRT doesn't get me there.

Hi Paula;
Who is your surgeon?

Well, it seems that 'D's' are usually the most suited for us larger framed woman.I am 38 band size, and a D suites me best, C's are just a bit too small for my likeing, but if I get to a c from hrt only, I would be happy :-)
I am not really in favour of implants, due to the 'maintenance' issue... If it was 'for life', it is something different.
Now if I don't manage to get to a reasonably acceptable size, naturally, I might concider them though.