For convenience purposes, it's best to rent a car to move around town. There are rental companies located at ONT and LAX airports. Taxis and rideshares are also available. Driving times from Los Angeles International Airport and Ontario International Airport take approximately 60-90 minutes.
If you have more time, explore Big Dalton Canyon Wilderness Park, a beautiful park filled with oak woodland, picnic tables, and trails that span seven miles; Galster Wilderness Park, where you can take nature walks, witness wildlife and view a collection of petroglyphs. Conversely, if you have less time, consider prioritizing South Hills Wilderness Area or Rubel Castle to ensure you see the highlights of Glendora's vast nature and history in a shorter timeframe.