Ice-Eyes, you just made my day with this set :DSazando has a lot of stuff over Latias; it checks Ghosts better and can't be Pursuittrapped due to its tyimg, and it's one of the few things to resist STAB combos like Ghost / Ground, Ghost / Fire and Ghost / Water (all of which appear on viable mons this gen) as well as the common coverage combo Ghost / Electric. Also, it gets Flamethrower; Latias has BIG problems with Nuttre and Sazando just laughs in its face. It OHKOs Scizor, Forretress etc. as well.
The set, I think, is probably going to be:
Sazando @ Choice Specs
Levitate
4 HP / 252 SpA / 252 Spe
Timid (+Spe, -SpA)
Draco Meteor
Flamethrower
U-Turn
Dragon Pulse / Dark Pulse / Surf
Latias' fighting resistance, higher Speed, higher Special Defense and Trick access are obviously going to be useful, but Latias is much less reliable in a metagame populated by Nuttre and Tyranitar to counter weather. It depends a lot on team, of course.
This is exactly what I was looking for in Sazando, and it covers soooo many things so well. This dragon is trully great. It can partner with ANYTHING with this set, hands down.