We rode the entire loop/route of the trolley, with a break at the old town stop which is where the trolleys begin and end. We went for lunch and a walk around the old town area before starting the ride back.
Our driver, Ronald (Ronnie), who we had for the majority of our journey, was very friendly and entertaining. He made the trip interesting and fun. We also learnt quite a lot of history about the various areas which the trolley went through.
It's definitely worth doing this ride early on in your visit if possible, so you can get an idea of the layout of San Diego and where you might want to take more time for further exploration.