I've found them in sunken trees during different times of the year, but by far the best areas I've found with the most crappies have been soft-bottom flats in 3-6 feet of water with sparse bits of vegetation from the previous year. They are nest builders, so they make nests in that type of substrate. I've found spawning areas where two of us caught fish for many hours non-stop until we just had to go home. A fish on every cast...if the fish came off while reeling in, just let it sink and another will grab it. Pretty insane. I went back to that spot year after year, and it was very reliable.