It is a pick your battles kind of event... I know for Orlando 2 years ago we made the mistake of buying too many autograph tickets and ended up in line for most of the convention only seeing two panels.... We ended up giving away/throwing some of our autograph tickets out (in Orlando some of the not so high dollar people just took 10 tickets up to their charging price).
In addition the celebration store was insane at Orlando, unfortunately my husband and I had wanted the autographs all on the same poster so we ended up in line for over 4 hours just to get the blessed event poster! (see picture attached)
Panels, the bigger the panel the earlier you need to get in line, in Anaheim if you weren't in line at least 90 minutes ahead of time for Mark Hamil's or Anthony Daniel's panels you weren't getting in, and the main opening ceremonies that also showed the SW:TFA trailer was a massive sleep over.
However Orlando is BIGGER than Anaheim, so I think panels and overflow will have more room, however the autographs and picture lines are going to be the same, and there will be more people fighting for those pictures at Orlando than either London or Anaheim. I heard from 501st members that have gone to all three locations for SWC and Orlando is the BIGGEST of all Celebration locations.
I can't say plan enough and pick your battles, but a MUST do list together and make that your priority, other items keep on list but know you aren't gonna be able to do it all.