My personal suggestion is that the entire perception system of 3e needs an overhaul.
Spot and listen should be cut back into a single "perception" skill. Why? Because so many monsters have abilities that are neither spot nor listen, and it really matters.
Naturally move silently and hide would be turned into stealth.
Every single monster should be cut back to a default of "normal vision" and deserving monsters should be given additional abilities
blindsight, scent, tremorsense, blindsense, low-light vision etc should all be modified to be bonuses to perception (up to +40 in the case of blindsight, so detection and pinpointing of invisible but otherwise unhidden targets is automatic). These bonuses should also have situations where they do not apply, or are reduced (ie - creature with blindsight that is in the area of a silence spell, and is trying to find a creature with some form of scent-defying spell will, unless the blindsight is magical, be relying on normal sight...)
Concealment should be a matter of the spot check - a sufficiently high spot check should defeat concealment which is not total. After all, it seems strange to get a 50+spot check to see a target in the shadows, but yet still have a 1/5 chance of not having seen him well enough to hit him with a weapon.
and so on and so forth
IOW - if you're going to do it, do it properly.