When starting a new document in SketchUp Layout, you have the option to choose a template in specific paper sizes. They are listed (Letter, A4, ArchD etc.), but don't include the specific dimensions of the paper sizes in inches or millimeters (you can still find them under Document Set Up). So below is a spreadsheet of the Template Paper Sizes in inches and millimeters for your reference.

For smaller spaces, I generally choose letter size so that I can easily print on my office printer and bring to a client. (My client will also be able to print these files easily). However for larger projects I like either 11 x 17 or 24 x 36, which I then send to a local printer.

Once you have added your logo and business information to a template, you can save that into the templates section. This will help you from having to repeat these steps at the onset of every project.

Saving a template in SketchUp Layout

Now, when you start a new file in LayOut, it will give you the option to start with a template that you have already altered with your logo and information.

Using a custom template in LayOut