I've been to both resorts many times. Definitely not the same trip, IMO. For a true Disney enthusiast, a trip to Disneyland (the original park) is a treat. Plus, most rides you find in both Disneyland and Magic Kingdom are superior at Disneyland.
And while I see the comparison of Hollywood Studios and California Adventure, I definitely don't think of them as the same park. California Adventure has a lot of unique attractions, and for all the bad press it gets, I really enjoy it.
The weather in California is so much better than Florida, especially in summer. Why sweat in the humid Florida heat when you can enjoy the pleasant SoCal temps?
And your desire to visit the local ballparks I can certainly understand. The Angels stadium (whatever the heck they are calling it now) is right down the street from the resort, and with some planning the others are within reach. That sounds like so much fun!
Don't get me wrong, I love WDW and am greatly anticipating our return there, but my advice to you is - why not visit Disneyland Resort? It's definitely not the same trip!
And from a fellow terrible flyer, Xanax works wonders!