MtheGM, I think you would have to admit that The Robot series and Foundation not only overlap, they dovetail: dovetail in such a way that the implication is that the 'bots have been there all along!

Yes, now that I've slept on it, so many I've overlooked!

All of the Sherlock Holmes

Yes to 900 Grandmothers which I have in an anthology, I've read many times.

1984, and only recently

The Left Hand of Darkness

Moby Dick (though not recently)

any Philip K. Dick opus, especially: Ubik; Flow My Tears, The Policeman Said; and Radio Free Albemuth

Mote (yes, all you Motie fans, and associated tales { "I will teach your horse to sing hymns"])

Sirens of Titan

The Prophet

many more with multiple readings, more than a few already mentioned by others above. Gee, maybe I'll start reading again!