Poetry.

Poetry makes me weak in the knees. You want to sweep me off my feet? Read me poetry-- even better, WRITE me poetry-- and be ready to catch me. How many times has anyone read me poetry? Umm... twice. How many poems have actually been written for me? ... one, that I can recall.
Of course, to read poetry to someone, you need to have a rudimentary knowledge of the contents of the poem. Especially if the one being read to is like me, and comprehends what is being read. The last thing you want to read to someone is a speech by Petrucio in "The Taming of the Shrew" about how he will make Katarina submit. Not quite the passage you should select, especially if you are reading to impress. The biggest impression left will probably be on your face... and it will be the impression of a shoe. Just saying.
Now that you are careful not to offend by your reading, you must take head of the emotional response your reading may initiate. For instance, if you read "Annabell Lee," I will be crying buckets by the time you reach the end. And although there are certain positives, seeming very caring as you hold your crying listener, you could instead be viewed as a highly incentive person who enjoys making people cry.
Normally, a work by Shakespeare such as Sonnet 18 ("Shall I compare thee to a summer's day...") would be the best option, but that is only in cases where you have honestly gotten to know the listener. If you read that to someone you don't really know, you may, again, end up with a shoe print in the face as she stomps away yelling "you don't even KNOW me, you scum-bag!"
Therefore, you are left with poetry that discusses no emotion... unless it is about a flower... written in such a way that it could not be miss-interpreted as a symbol for a girl.
If you had ever taken the time to think about this yourself, I applaud you... for people like you and I are few and far between. Poetry is an lost art, like love letters. It is one of self-expression but in a manner that is melodic, organized, systematic and pleasing to the ears.
If you think the realm of picking poetry is complicated, you obviously haven't heard that flowers all have different meanings. But don't fret... you have the internet.