Isla is pretty yet strong, and a name that sounds good on an adult woman too.
Amelie is lovely in a French accent, but it sounds a bit wet when used over here, IMO, along with a lot of the '-ie' names that are currently very popular. I prefer Amelia.
A friend of mine with a French husband has a Clemence (can't do the accent over the first 'E' on my laptop!), and I think that's also lovely.