Space Odyssey

One of the best collections of SF stories from the 20th century. Wells, Vonnegut, Silverberg... it's a great representation of the genre.
I recently found this anthology in a second-hand bookstore and I remembered just how much it had gripped me when I was a child.

It kicks off with Harrison Bergeron, which is probably the most familiar of Vonnegut's shorts, and
Rachel Pollack's “Is Your Child Using Drugs?” was frankly terrifying when I was younger and hasn't lost much of its power now that I'm old enough to understand what it's all about. The same goes for “Descending”, and “The Engine at Heartspring's Center”.

There's not a story here that I would hesitate to recommend on its own merits.