Early 80's Japanese mid level bikes like bike like Nishiki, Centurion, panasonic, bridgestone, univega get my vote you can keep them simple (friction or upgrade) easy to work on and good quality
easy to put a north style bar on for more upright commuting (and then use a thumb shifter)
both of these wold work, the bridgestone is a upper end model
and to be clear Steel frames are not heavier than aluminum
63 cm in bellingham $125
https://bellingham.craigslist.org/bi...945112402.html
loooks like a nice bridgestone $325
https://seattle.craigslist.org/see/b...953742405.html