I know that Prada Infusion d'Iris is popular with women, and is a very classy scent. And I like all the Hermès scents you mention, although I also like Elixir des Merveilles quite a bit. My wife likes both Prada and Hermès scents a lot.
Have you considered taking her out to the store and buying her favorite? You can take her out to the perfume counter after dinner and show her several Prada and Hermès scents (don't let the sales associate push her toward something she doesn't like). Then let her pick which one she likes best and buy it for her.. If it has to be a gift you buy first, then you can always pick one, but make sure that you can exchange it if she doesn't like it, then she can pick her favorite.