I have no problem with Zappos -- just Frederick's. Well, not really a problem, just slight shock that you suggested them.
But okay, since you asked, here's my advice:
If you want to get shoe's from a lingerie retailer, I'd go for Victoria's Secret -- I've have a pair of ballet flats I bought online from them that I lke a lot. They sell shoes in their house brand up to 11, though unfortunately it's a lousy brand. But at least they have some shoes that you can actually wear outside, and they occasionally carry shoes from other makers in 11 (generally just up to 10). Overall, you might as well buy from Target.
I don't really like Zappos, actually -- they tend to have lots and lots of of shoes that I don't want to buy. If I find a shoe online, it's usually by searching through a bunch of different stores -- Macy's, Ann Taylor, Steve Madden, etc. They usually have completely haphazard size selections -- but they also usually have search functions which allow you to pick a size. I've seen sizes up to 12 where I really didn't expect it.
But of course, it's always best to buy in person. Uncomfortable feet are unpleasant. I got a pair of cute, quite comfortable shoes from Ross a size down from what I usually wear (10 instead of 11). If I'd gotten them online, I would have gone for size 11, and they would have been too big. I have another pair of shoes from the same maker that also fit well. So in general, I'd recommend against buying shoes online.
Then again, I just bought a pair of ski boots online -- from Sierra Trading Post, in case you're wondering. 😉 -- which everyone says is a really dumb thing to do. Luckily they fit well, size 27.5. My feet are pleased. 🙂