A new chain may be noticeably better if the old one was rusted. If not rusted, then clean and re-lube the chain. It will be quieter and shift better.

New brake pads are a must. Be sure to sand the pads to give a toe-in configuration. Clean the braking surface on the rims, too. This should be noticeable when braking.

New tires, modern, light weight, supple tires, with light weight tubes will also be noticeably better.

Things like repacking the bearings is important for longevity but is unlikely to be noticeable (if done correctly). It would have to be done monstrously poorly to ever notice.

P.S. - don't ride on sidewalks, ever, you are not a child.