I use my player extensively in workouts-- sometimes up to 3 hours per day.
MUST have a player that knows where you were in the file when you shut it off, and MUST have one that works in a simple folder system. I've been very happy with my Samsung YP T8, and you can get them used on Ebay for about $30.
For what you want, you only really need a half a gig.
It doesn't hurt to have a voice recorder on the unit; you can use it for notes on what your pace, etc. were when it's not convenient to stop and use a pencil.
I use beats-per-minute rated music for my workouts. It really pushes the motivation. But I also use podcasts (both musical and spoken word), oldtime radio episodes, and audiobooks.
I like the audiobooksforfree.com site for books. You get to choose (and pay affordably) what sound quality you want and you can get them in zip files to make it simpler. It works on PaypPal.
GOGOGO!
Some runners I know prefer headphones to earbuds for workouts and runs. Shop around and you will find what you like.