Need starter help

I have a need to draw a very basic layout for a parking garage. Not the whole garage, just the flat layout. It’s fairly large at 300 feet by 120 feet. I just want an outline and then put some lines in for parking slots. It would be nice to show the dimensions also. So is SketchUp over kill for this? Can someone give me a few starter steps.

I would start with drawing a rectangle (R) the outline of the garage. Then double click that face to select it along with its bounding edges and make it a group (right click > Make Group) to avoid other geometry to stick to it. Then I would do the same for creating the parking slot. After that I would use the Move tool (M) in copy mode (Ctrl) to lay out the slots.

Linear arrays with the Move tool.