My last frame was a cheap aluminum poc, weld broke at the bottom bracket after 2 yrs commuting. This is what I came up with when I thought about what the ultimate commuting bike would be.
Surly 1x1 frame
Shimano nexus 7 hub (to see if I liked internal gears)
nashbar trekking bars w/reflective cork bartape
xtracyle attachment -the best thing i have bought for commuting/grocery shopping-going on 3 yrs old
spiderflex seat- weird but comfy
hokey spokes on front wheel, to get peoples attention when it's dark.
eno cranks 38t with a 16t cog in back
extended my fenders to reduce water/salt spray