bluerfoot,
Sony's "premium cover" (
PRSA-SC35) conforms tightly to the reader -- it's probably the tightest fit you'll find.
It should protect the screen well, but it's "drop" protection is probably very low. unfortunately, that's a trade-off with covers -- "very protective" or "light and small."
Also, Sony's brackets do wear with inserting and removing the reader. if you always leave the cover on it won't be a problem, but if you like taking the cover off when at home it will break sooner than you'd expect.