Running one train is good, but why not run two? And then, why not run them both on the same track? Enter Cab-Control. Using this system, the track look is set up into blocks, or electrically isolated areas of trackage. (To isolate it electrically, use plastic rail joiners or cut the rail.) To each block, run each its own separate pair of feeder wires. Attach the feeders to the center poles on a DPDT (double pole/double throw) switch. Then attach the wires from each cab (a separate powerpack or controller) to a separate end of poles on the switch.
If you're a tactful electrician, you can power a common rail and then simply use SPDP switches.
To operate it, you'll need a minimum of 4 blocks: a locomotive must have the one it occupies and the one ahead of it (so it won't stall when making the transition) powered. Advance the throttle on each so the trains run, and switch the DPDT switches of the block ahead of the locomotive. This means you'll have to pay close attention to when the trains cross borders between blocks. Some modelers put trees or objects near the boundaries so they'll know ahead of time to throw the switch.