I'd recommend getting as far away from Sassoon and Owen as possible! Our newly-qualified English teacher, for O-level, had just left university, where he had written his thesis on the First World War Poets. Consequently, there is a whole class of his ex-pupils who never want to hear the names of Sassoon, Owen, Brookes and Graves ever again!!! (My god, were we bored!!!).
The classic anthology of English poetry is Palgrave's Golden Treasury. Scroll down to 'OUP Edition' to see the poets featured in it:
http://en.wikipedia.o...e%27s_Golden_Treasury
With all of those poets (and 720 pages) there must be something there which you'd like and, at under six quid from Amazon, it's a real bargain!
http://www.amazon.co....qid=1315185358&sr=1-1
Chris
(PS: Try some of D H Lawrence's poetry. I love it!)