[bethohio3]

Actually, you were right--I used iTunes.

To do this, I saved the books I wanted to load (in sets of 200) as EPUBs in a single directory.

Then I dragged them into iTunes for the Marvin App.

I now have all of my books loaded and it didn't take as long or need as much clicking as selecting them one at a time from Dropbox would have.

Thanks for pointing me in the right direction.