Oh, and of course, Eric Frank Russell....
Also, you might want to look for an old series of books brought out in the 1970s, The Best of..., which began with a collection of Stanley G. Weinbaum's tales. This covered a pretty representative selection of sf writers from the period, and the selections were indeed very good. They were put out by Nelson Doubleday in hardbound, Ballantine Books in pb; and were also put out by the Science Fiction Book Club, if you're looking for less expensive editions.
(Speaking of which, let me put in a word here for the book club editions issued by such as the SFBC, Mystery Guild, etc. Though they've received a bad rap, the fact is that they often hold up as well as many of the more expensive editions -- in fact, I've often seen book club editions where the paper browned or yellowed less than the regular editions -- and are often easier to come by and less expensive when you do. So you might think about looking into this as one way of finding something sturdier than paperbacks when searching for older books in the genres....)
