You will have to take Uber to get around. The Queen Mary is right next door. You can get on for free and walk around if you show your cruise card. Tours are $10. Make sure to show your cruise card at the ticket counter and they will send you upstairs for cruise pricing. ...
Long Beach was just another "ok" stop. Being a California resident, if I want to go to LA, I would fly there or drive and stay at a hotel to then go sightseeing. The port is about a 1 hour drive from Los Angeles, so you are looking at 2 hours minimum spent on driving. We did visit the Queen Mary, but mainly because that was all one could do at the Long Beach port. ...
Busy shipping port of San Pedro in Los Angeles area - World Cruise Centre, Just stayed overnight day before cruise - not a great as very industrial and lots of traffic ...