That's something I'm really tired about in 3.5: Having to think about every little piece of loot, and continually checking with the players that they are around the wealth guidelines.
Boy, you said it. Having magic items a solid part of the math will go a long way to making sure the group is just where it needs to be. I remember reading in a designer's blog about how magic items will have a level attached to them so it's obvious when they are intended to be used. And he also said that deviating from that intention in either direction won't wreck the game.
