Wow, I was flying with my younger brother when I was 6 years old (with airline staff escorting from gate to gate, until I was about 12 or so)...but everyone is different. I agree with Irulan to perhaps consider letting her navigate herself through the airport on the way back. Just an idea; not my kid, I get that everyone has their own style. My own brother (who flew only with me starting when he was 4) just this year sent his kid to overnight camp--at age 11! His daughter at 13 still hasn't been to overnight camp. I was going to overnight camp at age 7 and loving it.

I hope your daughter has a great time. Perhaps she can go to Spanish immersion camp in Spain/Latin America next year, for a month at least, living with a local family...that's the best way to learn the language and culture, and having a good base beforehand makes it much more enjoyable.