So for me - the option is clear to run home from the train. There are multiple options, some I will consider in more depth as I look to extend my mileage. But for now the point here is the gear. At it's basics, you'll need to carry whatever you need to carry on a daily basis and you'll need hydration and transportation covered.
To cover these I purchased this bag:
It has two waist pockets on the strap, a chest strap, a back zippered pocket for a camelpak (if you have one). There are three compartments - outside (the one where my shoes are), a front pocket with zipper pockets and a larger back compartment with more zippered and sectioned pockets. As well there are two mesh side pockets - for my umbrella and sunglasses or whatever. It also has compression pulls to help the camelpak flow when it gets towards the bottom (those clear hoops - see right side of the photo).
As for storage it's great! I have no problem finding room - the problem is having too much stuff in it. It is the perfect size for a petite frame, regardless of your weight, I will say that if you are broad across your chest, adjustments will need to be made. I am petite frame wise on top (32 C/D) and the strap fully extended just fit right. The waist strap had a lot more room, which I found a little weird, but it would easily fit a size 12/14 waist.