Not sure children's books would be the most interesting for adult travelers, though they might be fun for doing chores at home. For intermediate listening and pronunciation, I often suggest songs, whether children's songs, folk songs, or well-known pop songs perhaps in a folky style from a few decades back (i.e., slower and quieter). It does help if you can look up the written lyrics at least once, so that then you recognize the words when sung.
For spoken text I'm afraid I can't personally recommend a particular source, but I sometimes find that just search tips are helpful. Here are some ideas just in case you could use audio made for English speakers, which might be more widely available.
A quick search on "learn Spanish" + "podcasts" brought up almost an overwhelming quantity of hits. You might be able to go straight to iTunes or the Grrgle store and get some ratings for comparison, and just try out a few.
I might also be inclined to search for audio from established publishers or sources, such as travel guidebooks / phrase books (Berlitz, Lonely Planet, Insight, DK, etc.), public broadcasters (the BBC has many language courses, not sure about DW), or academic institutions (for universities you may still be able to use "site:.edu" or "site:.ac.uk," or I believe the Instituto Cervantes is the counterpart to the Goethe Institute).https://www.cervantes.es/default.htm
Some courses advertise as a feature that the audio part is just one component of a systematic approach with additional written and video materials, which I can understand might be less useful to you. However, if the course were good, you could always just use the parts you can and ignore the rest. Or see if any of the written components happened to be in a format like .pdf that has a read-aloud function.
Many podcasts specify that they're meant for intermediate and higher learners, which makes sense. Part of the question might be whether you feel your individual grammar and listening level is already strong enough to be able to follow longer complete texts in paragraphs (news, features, stories, etc.), or whether you would rather focus first on shorter phrase-book-style sentences, such as conversational material especially for travel. Searching on another term such as "conversation(al)" or "dialogue" might be a way to get more of the latter. Searching on the former with an added term such as "simplified" or even "slow" might also be useful. There is or was actually one company that produces "slow" (-ly spoken) news in several European languages -- "slow Spanish," "slow French," "slow Italian," etc. -- but I'm not sure Greek is among them.
Just trying to help brainstorm; hope that's some use. (-: