There is such a vast array of lovely wedding poetry out there that you may find yourselves spoiled for choice! Alternatively, you might find yourselves having to wade through huge numbers of unsuitable readings (some religious, some cheesy, some just badly written) on the internet. There are some very nice wedding poetry books on the market though and I particularly like, 'Handfast', which is a book of Scottish poetry for weddings (published by the Scottish Poetry Library in 2004) and 'Heartsongs' by Pinky Agnew (published by Rider, 2006). The Humanist Society also have a huge collection of lovely non-religious poetry and readings to help you to find something appropriate for you. The most important thing is to choose poems that you like and that express your thoughts and feelings about each other and about your wedding day. Many couples chose to have 1 or 2 readings in the ceremony, but you could have more and of course you don't have to have any at all if it's not your thing!
You also need to consider carefully who is going to read for you.