Also i have a breadboard attached to my uno like in photo then you have TWO ground rails plus TWO Plus rails, one can be 3.3 other 5v with lots of space for switches and other sensors, LCDs etc.
Be mindful of the breadboard some have 5 skts per column other 6 skts per column.
Six is better when you use board like NANO. Also something like this shield may really help as switches and LCD to display the ultrasonic range etc
