Bonus Skill: Traveling
I have an idea for a bonus skill that you can buy from the lingot store. It focuses on things that would be very useful when traveling overseas, such as phrases like "I'm allergic to shellfish", "Where's flight 104?", "Could you take a photo for me?", etc.. Even if some of this does exist in the Duolingo skill tree, I think it should be accessible to people in early levels, especially if they are going overseas in a few months. [Quick Edit: The English for Spanish course includes "Trips" or "Viajes" early on.]
I can see why you want that. I can also see why they don't do it. Duolingo is more a full beginning level course rather than a quick and dirty way to learn travel vocab. There are already lots of phrase books out there that do this (and plenty of free websites). Obviously, they don't do it with Duolingo's method, but I am under the impression Duolingo want to do a full course rather than just have people sign up, come a few times, go on holiday and never come back (I am not Duolingo though, so that is not an official statement, just my impression from using it for a while).
Also, most of those require understanding the response. I suppose learning how to say you are allergic to something is useful even if you can't understand a response, but things like 'where is flight 104' - if you have not built up some oral understanding, being able to say that is only so useful without the skills the understand the answer.
Soy alérgico a los mariscos "," ¿Dónde está el vuelo 104? "," ¿Podría tomar una foto para mí?, son muy buenas preguntas, talvez podrian agrgregar: ¿Como llego al hotel Lincon? , ¿Esta muy lejos de aqui?, ¿Donde encuetro un taxi?, ¿Donde hay un restaurante? Es my rica la comida de aqui, etc...
You might enjoy "Mi Vida Loca" from BBC. Twenty two (partly) interactive episodes of a foreign adventure in Spain. http://www.bbc.co.uk/languages/spanish/mividaloca/ep01/index.shtml