If you don't already have HO stuff, I heartily recommend starting with the 4-Way Split set. These two layouts just use parts from the 4-Way Split. You can use the extra cars as spares/parts, and you can use the duplicate controls to have separate power for each lane of a two lane track (use both power terminal tracks, and just plug one power pack and one controller into each power terminal track). With either of the following layouts, you'll have lots of great track sections left over that are expensive to buy separately and hard to find in other sets (you can easily trade them, sell them, or use them in other track projects).
The big difference between these two layouts is that the separate control stations are either on the same side or opposite sides of the table.
The 4-Way Split set comes with Tomy's lap counter, but I don't recommend using it--especially if you're planning on permanently mounting it.