Well, I have a few comments which might help.
First, what kind of analyses are you looking for? You mention the fact that you are trying to analyze a work before sitting down to play it, which gives me the impression that you're looking for specific musical structures, cadences, etc; in other words, you're trying to examine the piece in a way which will help you develop your performance of it. If this is the case, then I doubt that a "formal analysis" will help you much; in my experience with academic journals/books, these formal analyses are often very dry and scholarly, and typically deal with specific musicological issues. They have rarely helped me with my performance practices. You will probably be better off with more general reading on music theory, which it sounds like you already have; developing a base understanding of the material is probably the most important thing.
With that said, I do think that it is sometimes interesting to read these scholarly articles, and so I have a couple of recommendations.
I can offer a suggestion for an excellent book on one of the composers you mentioned: Bach and the Patterns of Invention by Laurence Dreyfus (Harvard University Press, 1997). I once took a graduate course on J.S. Bach, and we used this book as a "textbook." I found that it was a very good resource on everything about the composer, and it offers numerous in-depth analyses of specific works. These alanyses, however, typically relate to the specific topic that Dreyfus is dealing with in the particular chapter, often pertaining to how Bach fits into the historical fabric of musical culture/compositional practice. As such, they may not be what you are looking for, specifically. But the book is interesting and informative, nonetheless.
Other than that, you would probably do better to go to the library and research the specific piece you are looking at, and find journals/articles by searching for that piece. There are many, many academic periodicals on music, and their contents are broad and varied, and so naming some of them probably won't help you. Glancing over the footnotes of some of the papers I wrote for my music classes, however, I'm seeing the Journal of Musicology and the Journal of the American Musicological Society appear most frequently.
If you have access to the university library and you are looking for this kind of thing, bring a list of pieces/composers/topics you want to learn about, run some searches and see what you find. There's a wealth of information out there, 90% of it I'm probably not even aware of, so your best bet I think is to go hunting yourself.
Good luck!