I don't think that the Vypers would be an effective option, since I feel that they work better when equipped with a longer ranged weapon than a Shuriken Cannon, so that they can keep out of the way of rapid fire, and many assault weapons.
The Spiritseer is an option, but I'm not sure how useful an option. Given that it's a new option though, you could experiment with taking him/her to see what happens.
Outflanking Striking Scorpions are not something I recommend with the assault rules as they are.
I like the idea of the Warp Spiders, or Swooping Hawks, best from a tactical point of view. While they do run the risk of being targeted when they arrive, by including the Autarch you do increase your chances of being able to delay the deep strike, so that they don't arrive too early. This would, hopefully, mean that they wouldn't get shot up by arriving on turn two on a regular basis. Even if they were to arrive early, you deep strike them behind your transports to protect them if no suitable line of sight blocking terrain were to present itself.