The biggest issue with taking public transit to school/work is the management of all our STUFF. Every day between TRex and me we haul her lunch and security blanket plus swimming stuff on swim days, my lunch, all my teaching stuff (including computer and purse-type-gear) and my gym bag.
M had volunteered to take my work stuff with him so I would only have my gym bag and her stuff to contend with, but that would have created the need for another bag for purse-type-stuff on the way to/from the gym.
But then I realized that my thinking had been too compartmentalized. I am now down to two bags for me and one for the kiddo. My two bags: backpack with computer in small laptop bag and my gym stuff, and my new perfect bag with purse stuff, books, and lunch box. Her bag: backpack with all her misc. stuff. I'm working on convincing her that big pre-K kids carry their own stuff, but this morning it was legitimately too much for her to carry the whole way from the train to school - swim stuff plus nap stuff plus lunch.
And I'm still in love with my new bag.