The setting always dictates details of race. If I do attempt a 4th edition campaign, it will have to include all the races that I currently use in my OD&D campaign (elves, dwarves, gnomes, halflings, faeries, merfolk, centaurs, fauns, and birdfolk).
As far as character classes go, though, I like a less-is-more approach. And what with classes being based on powers now, it shouldn't be too hard to turn, say, paladin, ranger, and warlord into fighter paragon path options. At the bare minimum, an RPG needs warriors, monks, healers, thieves, and wizards. At the maximum, a bard-/marshal-type, an artificer-/scientist-type, and a psionic-/illusionist-type might be thrown in, depending on the setting.