That's a tough question, Ron... and it really is lot specific. Obviously areas near a water body that are in a flood plain are highest risk... the ones that require you to carry flood insurance. Terracing does work for steep lots, but is very expensive. Depending on how steep/how tall each terrace is, it may have to be permitted by the county. As far as streams, I wouldn't say they are a risk, but it would depend on how close the house is. I saw a house last week with a creek running through the crawlspace. No kidding!
I know that doesn't fully answer your question, but I would have to look at it on a case by case basis. Are you looking at really inexpensive lots? The ones that are the hardest to develop, or have issues like you mention above, are going to be in the lower price ranges. You may try looking up in price range a bit and see if there is a difference.