I'm doing Wild Swans at Coole and The Second Coming, and then either Sailing to Byzantium or When You Are Old(Depending on the question).
I find Wild Swans to be an easy-ish poem, filled with a lot of techniques that show his feelings at that time in his life. Feeling he'd lost his poetic touch and love etc. etc.
I also find The Second Coming great, as there is much symbolism, and it highlights the fear of what may happen to the world after war and destruction. I don't know, they just seem great to me.
The questions asked since Yeats was introduced in 2004, have only asked for 3 or more, once - in 2005. In 2007 the question could have been suited to most poems(one intense human emotion, using TWO poems). In 2006, it was a quote about age and youth in Yeats poems. That kinda directs you to which poems you can use. It asked for TWO once more, however you could use the Byzantium poems, or I guess When You Are Old and Wild Swans at Coole. I know which one would probably get the better marks...hmm. heh