I would LOVE to play an Iyanden army. They are so totally badass, but I never have the money. My opinion for your army is to go with multiple smaller squads of Wraithguard to screen Wraithlords, and at least one Wave Serpent. You should probably keep the Wave Serpent in the back while your Wraithguard engage the enemy, and each time they are about to overpower you, send in more troops- I have found that enemies will not commit to a major attack unless they see you have most of your troops there, especially with Eldar. Since WG are extremely strong individually and like Termies in groups, that means your opponent will sorely underestimate you and send in weaker squads which will be chopped to bits. When they get around to bringing their full firepower to bear on you, move up a Wraithlord or two to balance the equation. The Wave Serpent troops should be going after long-range support from your opponent.