Typical connotations of the word “rationalism” seem very unfortunate to me. Rationalism ought to mean something like just giving pride of place to reason (inference). Instead, it is usually taken to refer primarily to what I would regard as aberrant historical versions that carry unrelated and even antithetical baggage. I have in mind particularly Cartesianism and Wolffianism, both of which make dubious claims based on allegedly self-evident contentful truths.
At most, I think something called “rationalism” should recognize self-evidence only in a narrow formal domain, and I think even that is arguable. Otherwise, reason works from evidence, not self-evidence.
Although he did use the unfortunate phrase “evident from itself”, Spinoza was much more careful. He thought most of what the Cartesians and Wolffians claimed on the basis of self-evidence was not even true. Leibniz was a great explorer, and proposed not one but quite a few differently detailed systems at different times. (See also Enlightenment.)