Fixing Bluff? (D&D 3.5/Pathfinder)

So, I was browsing around the site earlier and stumbled across the old gaming articles thread from the Giant (this one). And I found I really agree with the new diplomacy system, especially the idea that everything should be balanced around someone optimizing themselves for it, not just the average unoptimized character.

Thinking about it some more though, I realized Bluff has similar problems. Sure, it's opposed by Sense Motive, but that just means it's even chances if both the player and the target have max ranks in their respective skills, and against any NPCs that don't have ranks in Sense Motive, it's too easy.

So, I want to try and fix it, make it usable but not overly broken by someone that maxes ranks in it. (Keep in mind that I'd be using the new Diplomacy system from the thread I mentioned earlier.)

One thought I had was that Bluff could essentially replace Diplomacy checks, depending on what the player is attempting to do. It would be a check against two different DCs; the first as the target's Sense Motive score, to figure out that the player is lying, and the second treated as a normal Diplomacy check, just using the character's Bluff skill instead. (The player only makes one roll and compares it to both DCs.) If the Sense Motive check fails, the NPC knows the player is lying, the other half of the check automatically fails, and Bad Stuff happens. If the Sense Motive check succeeds, then the check is compared to whether or not it's worth the NPC actually going along with what the player suggested. More outlandish lies have an easier chance to be detected, but if not, they have an easier chance of actually getting the NPC to do something.

Has anyone else found some good houserules to make Bluff work a bit better?