I know I need more practice or better artistic sense.
I have already seen one, and all I can say is, you need to ask what we think before you take them off Direct and slap an ISBN on them. It's now too late, really.
Myself and my friend combined know everything there is to know, but he's not here.
My advice would be to read more and to join a writing group.
And do a lot more research. Never publish facts that are not facts just because you think they are.
I surely would work harder on those covers.
I also would not include color art in a POD book unless it is absolutely necessary to do so. Ten dollars is much too much to pay for a book of only twenty pages.
And speaking of the visual nature of your books, you also need to take more care with the typography. Take a look at traditional books and emulate them. As it is, the text of your "Big Book" is almost unreadable....or at least unpleasantly so. The "Lil' Book" is only marginally better. Again, use a traditionally published commercial book as a model. For instance, look at how paragraphing is handled.