I should mention, the small breadboards without with the external red/black power rails are useful if you get a proto shield, as it fits directly in between the rows of pins. You don't have the convenience of having the power and grounds near the rows, and you will have to bring them forward, but if you switch from project to project, you can put all of stuff for one project on the breadboard and shield, and just remove it to switch to the next project. For example, this is a revision of my telegraph shutter key:
However, if I'm doing breadboard work without the proto-shield, I tend to prefer the shields with the power rails.