I agree w/ Cameron that in perpetual leagues, the quality of picks drops off quickly, but you can usually expect to find 2-5 quality starters, an ace reliever, and a couple of solid position players in the pool. I will very often try to trade for #1 FA picks in either hopes of nabbing a top flight player or protecting my core roster (relying on FA picks, not the end of the rookie draft to build my team).
After round 1, I either look for diamonds in the rough or solid role players. Last spring, one team drafted Brad Fullmer and Mitch Melusky in rounds 2 and 3. Another team drafted Doug Johns and David Delluci in round 8. Johns had a .400 OBP vs. LH batters and could pitch everyday. He put up a 2.70 ERA for me in over 40 innings of work. Delluci did nothing but pinch-hit for me and had a +.500 OBA.