What site are you using to look up flights?

There is a bit of knowledge to learn about flights. By going big, I m assuming you want something more than just domestic first - i.e. lie flat seats? Or are you also looking for premium service as well? Fortunately LAX and SFO, especially LAX, have some premium flights, but they are not cheap. My preference is always for wide bodies (twin aisle aircraft), but there are now some single aisle aircraft flying with premium (lie-flat) seats too. I don't know if any of them fly direct to MCO, though, so you might need to make a connection.

If aircraft type is important to you, I would highly suggest ExpertFlyer. Not so much for flights, but it is going to show you just about every flight option between two airports out there. You can then use that in a site light ITA matrix to get prices.You will want to learn the aircraft type, though.

777, 772, 77w are Boeing 777 wide bodies. Most of these have some kind of lie flat seats (though be careful - some UA 777s only have domestic first seats)
788, 789 are Boeing 787s - definitely decent seats on these
359 are Airbus A350s, good seats on those, though not a lot flying domestically
33x - Airbus 330 familly, are also good, if anyone still is flying them.
The other planes that will have lie flat seats are any JetBlue Mint class planes (any of them have lie flats), AA aircraft with the code 32B, Some UA 757 (though certainly not all, you have to check each one, unfortunately), and DL 764 and 76W.

To get the best inflight service you need the premium routes - LAX to ATL on DL, LAX to MIA on AA, LAX to JFK/EWR on any, LAX to FLL on JetBlue,. and LAX to Washington Dulles (IAD) on UA. Every once in a while you will find one flying between LAX and CLT or PHL, but these will not have the premium service.You might also find some of these on the SFO routes, but not all get that level of service.