Too limited
This is a great concept, but it needs much more. First of all, you could really use a fine volume/bass adjuster, then have the ability to layer multiple tracks. If you're doing transitions, make sure they're smooth ones that aren't [too] noticeable. You should also have some static in there, and not like just one option, but a variety of different electronic feedback: radio, television, guitar, busted speakers, etc. Iclude more than just ocean and forest sounds; why not get a recording device and just leave it next to an open window in the city, an pen door when its raining, or in a diner for like 20 minutes? Well, not actually leave it there... you know what I mean.
In short, this would be great if it had more than four options, two of which were probably off of some novelty/new wave CD.