Avoidance isn't so much the issue I think. Isn't that already handled by the attack rolls, ect? There's three general ways to avoid a trap.
1. Go through it and hope whatever mechanics are running cause it to miss you/allow you to dodge/fails to penetrate your armor.
2. Go around it, if you know it's there.
3. Disable it before it even goes off.
I think most of #1 is already happening. #2 isn't possibly in adventure mode when dealing with your average player fort. In terms of however Toady is distributing traps at sites, I'd say it already works fine.
#3 cuts to the heart of the issue. Traps reload indefinitely in adventure mode, do they not? Because traps are ultimately there for Fort mode right now, they're set up to work best for it. Goblin choppers, whatever. When they miss in fort mode, it would suck to have to assign dwarves to go reload that trap. Maybe dwarven traps are just so awesome they're self balancing and instantly reset, like the ones in Indian Jones and the Last Crusade (versus the boulder in Raiders of the Lost Ark).
So that's what I think really needs to be addressed in Adventure mode. Traps in adventure mode need to be things that fire off and are done. The blades/spears/spikes shoot out and stay out. The cage trap comes down and stays down.
Cage traps need special consideration because we expect to be able to break out of some cages but not others, based on strength of the character and the quality of the materials its built from. I don't doubt Toady is cognizant of all of that, it just hasn't figured large enough in the current arc for him to sit down and flesh out. Depending on how much traps come into play at these sites, he may still not feel it's enough to warrant what I'm sure is a re-write of some sort.
If he did though, all those things also logically lead to a simple trap disarming skill, which tries to activate a trap safely while you're on the tile and set it to off. I imagine what's not happening right now is that traps aren't writing any information to the site file. They just exist and have a function and don't update in any sort of way.
It's also worth noting that as soon as we're allowed to create sites in adventure mode, people are going to want to add traps to them. And that's going to bring the issue back again of traps going off and staying off, or not, and how much of a pain it is to end up with two different versions of the same thing in fort mode vs. adventure mode.