So I just discovered Halcyon Classics' Golden Age of Science Fiction ebooks, and I can't tell you how much I'm enjoying the first one. Out of the fifty novellas and short stories, I think I've read maybe one or two. The others are all new to me, and while they're not necessarily as good as the same stories you've seen collected over and over, this is more than made up for by the fact that you haven't read them. I love "Nightfall" and "Lifeline" and "The Fun they Had" as much as anyone, but I don't actually want to read them over and over again for the rest of my life.
Halcyon Classics' "Golden Age of Science Fiction" anthology contains 50 short stories by over 40 different writers