I'm looking for sf/f book recommendations

I have a friend who apparently wants to get more into SF/F, and possibly into conventions, and I'm going to build a reading list for her. Fortunately we have two great used bookstores here and one fair one, so getting ahold of older SF shouldn't be a prob.

Yes, there are numerous lists online, I wanted it from my friends. :-)

Some that I'm going to recommend are:
Asimov: I, Robot
Harrison: the Stainless Steel Rat trilogy
Heinlein: The Moon is a Harsh Mistress
Pratchett: the first Discworld trilogy
Zelazny: The Last Defender of Camelot
(Yes, I obviously have pretty old taste in books)

There was a Heinlein collection of short stories that I'm trying to remember, I know it had By His Bootstraps and The Man Who Traveled In Elephants, was that The Past Through Tomorrow? Did it have The Roads Must Roll?

Her main exposure is Star Wars/Star Trek/Battlestar Gallactica, so I'm trying to expand her horizons.

Come to think of it, Scalzi's Old Man's War would be a good addition.