I loved Maggie Smith in Private Lives and Night and Day in NYC, loved her in The Importance of Being Ernest, The Lady from Dubuque, A Delicate Balance and The Lady in the Van in London (the benefit of working for a huge international firm).
But, most of all, I recall the pure joy of watching her with Margaret Tyzack in Lettice and Lovage, twice at the Barrymore. Her performance in that was arguably the greatest comedy performance I have seen on the stage. She may be the only person who really could entertain you by reading a phone book. Imagine all the withering glances, the vocal games she would play, etc.
I guess that we can keeper fingers crossed.