Alhambra is best explored by car or Uber/Lyft. Parking is available near all tourist spots listed. Be aware of travel times during rush-hour.
If you have more time, consider adding a trip to the Alhambra Park, the Edwards Renaissance Stadium 14, or the Alhambra Farmer's Market. If you have less time, consider skipping the San Gabriel Mission or Main Street Downtown Alhambra.