It's actually the other way around. I really want to get the 5 (there's really no rational reason) but my mind says the 4S. So honestly, I want someone to convince me to get the 5.
Aside from durability, is there any reason you're saying the 5 will last longer than the 4S? The 4S will be a brand new phone too (brand new in the sense that it's unused).
This was one of the factors I was considering too but I don't think I'd buy any accessories. I can't think of any use for them.
----------
I don't think the scratches/scuffs would bother me. Does scuffing the antenna band hurt the signal quality or anything?
There are a few advantages to 5 that I have noticed so far. One is how light it is. That is nice. The other is that it has 2x the ram....so things don't fall out of memory so easily...which is very nice! I'm sure over the next couple years the extra power in the A6 will become useful too.