I live in San Diego and went to Universal Studios in Orlando
I use a Tamrac evolution to carry my stuff (MK III 24-105; ex430; 70-200; filter; battery...etc.) on the plane. When it came time to hit the park, I take the III, a lens, flash and battery--leave the rest in the hotel room.
in other words, i pick what I will use and carry that--much lighter. Actually, the extra space in the backpack is used for the junk the kids buy.
I also use the sun sling strap.
Its always tempting to want to carry everything but you rarely use everything.
enjoy San Diego