If you want a survivable custom world, you could check out the map I uploaded about a week ago. Although it is lacking in caves (they're there somewhere I swear!) it should have the standard resources and ores available. And I feel morally wrong using blocks for purely aesthetic reasons, so you won't find any trees made of glass or mountains made of solid iron.
Anyway, if you take a look at it and see something that makes survival mode impractical, let me know. I'd love to improve on that kind of thing, and am open to helpful criticism.
