In the daily driven, lightly wheeled, world... body lifts are great. They can make you higher, and they are pretty cheap. You can do a small suspension (tbars/aal), and a body lift and run 35's or 315's. Or you could go with a 6+3 deal and run quite large tires. They look good, and keep your hitch lower, if you ever tow anything. I realize you can get drop hitches, but the longer that drop hitch is, the weaker it can be. Also, if you have a roll pan, it's quite easy to turn your hitch upside down to have it hidden. I've seen it done. If you don't do any hardcore fourwheeling, you won't have any problems.
In the rock crawling (and hardcore fourwheeling) world, body lifts are not great. Even in mud with lots of power. I saw a K5 with a great body and frame with a body lift fall apart in a MUD PIT. He had tons of power, and hit a small mud "wall" in the pit, and the body came off and landed sideways on top of his frame. The consensus (sp?) was that it was due to the body lift. In rock crawling, they serve no purpose. We keep our centers of gravity low, and we need to articulate well. Body lifts still leave the suspension at stock height, and will not increase suspension travel at all. Some people will get a 1" body lift, so that they can fit things between the body and the frame. Like clocking a second transfer case up for ground clearance, or something to that effect. If you are going to wheel it pretty hard, I'd try to keep the suspension lift to a max of 6", and keep the body lift to a max of 1".
If I wasn't planning to do an SAS in the next 6mo-1yr, then I'd have a body lift on my Tahoe. But I have a feeling that the Tahoe will be getting some wheelin action that's a little bit more hardcore then barreling through cornfields, running through ponds and mudpits, and wheeling on some light trails.