yes I will be mobile. I will be driving from Long Beach to Irvine so anything within the general area is something I would consider. Off the top of my head some ideas would be a lunch cruise, live musical, comedy standup, or play but obviously I'd assume those would be extremely hard to find on a weekday afternoon.
A walk on the pier and sand can be a lovely couple of hours.
Or buy a picnic at a local deli or grocery store, then rent a Duffy (small electric boat), and enjoy your picnic on the water.
You might like a gondola ride in Naples (Long Beach) http://www.gondolagetawayinc.com/ Lunch on 2nd St. Belmont Shores (Long Beach) or Seal Beach Main St. Then you can stop at the Bolsa Chica Wetlands for wildlife viewing, Huntington Beach Pier to watch the surfers and volleyball players. You can also eat there at Ruby's at the end of the pier. Follow PCH down to Newport Blvd, go north to the 55 Freeway to go on to Irvine.