My priorities:

1. bottle cage + bottle. If you're in a hot place, times 2 or 3 or get a camelback
2. bus fare (and stay on bus routes) OR patch kit + levers + pump (spare tube{s** + spare tire for really long rides.
3. multi-tool
4. glasses
5. helmet

Everything after that is just niceties. I still ride my Pinarello with clips/straps/running shoes. Regular shorts and shirts work fine too.

Maybe switch #1 and #2. You can ride from water fountain to water fountain if you plan your rides right.