Florida Nemo vs. California Nemo? They are similar in that they use the same characters and some of the same technology, and even some of the same lines of dialogue are used in both rides. Florida Nemo is a 4 minute Omnimover ride and California Nemo is a 12 minute ride underwater in a submarine, so even though they are sometimes similar the overall experiences are
very different.
Why not ride both and then decide?
As for rushing to Nemo to get in line first thing in the morning, that is sooooo 2007!

You can spend your first hour in the park far more productively than riding Nemo. I love Finding Nemo at night, and in the evening the line begins to die off rapidly. You can head over there during the last hour of the park operation and usually find a 15 minute or shorter line. I like the ride better after sundown because the outdoor lagoon scene looks better all lit up at night, but that's just me.
As for other tips....
Fasptass Indiana Jones, Space Mountain and if it's a weekend and/or busy Fastpass Roger Rabbitt and Autopia. If it's warmer than 75 degrees, Fastpass Splash Mountain as well. Otherwise, you don't generally need Fastpass for Thunder Mountain and Star Tours.
Matterhorn Bobsleds, Peter Pan and Pirates don't have Fastpass at Disneyland. Matterhorn and Pirates you don't need to worry about as the lines always move very fast, but Peter Pan is definitely one you'll want to do first thing in the morning. (It's closing for a month of rehab in May though).
At DCA you'll want to Fastpass Soarin' and Screamin', and maybe Grizzly River Run if it's very warm. You generally don't need Fastpass for Tower of Terror or Mulholland Madness. Midway Mania doesn't have Fastpass at DCA.