For me? 35. I am no where near the energetic young thing I was in my 20s, and now in my 40s I'm tired, darn it. I would feel guilty if I'd had a child any older than 35, because I am just not the fun mom I was then.
I would totally do breast augmentation, if it didn't have to be redone every so many years and the weird health risks from foreign objects in your body weren't so many. And if it would not look ridiculous...which it would. I used to have small, but cute books. Nursing gave me non existent, wrinkly old toddler socks. (isn't that a lovely visual? Sorry!) But every one I ever met who has my size frame (very slight, boney) who got augmentation looks ridiculous, they look like bolted on flesh color balloons. Even celebrities (who can ostensibly afford the best of surgeons) end up looking like that- think Tori Spelling. So alas, it's padded bras and tricks for me. I suppose it's safer anyway, and certainly cheaper!