Usually when writing speeches for clients I come across two distinct types of people: those who really want to ramp up the emotion in the speech and make people cry, and those who really rather do not. There's nothing to predict what type of person you are; I have written for hardened military men who much prefer an emotional tsunami, and very bookish accountants who baulk at the thought of saying anything too 'mushy'. Of all the speeches on the day, the father of the bride speech has the greater potential for emotional moments. It's a big event in anyone's life - officially recognising your daughter moving on with her life leaving your family to start her own. The memories and recollections of years gone by, can be incredibly moving, and there's nothing wrong with that.
The problem comes, however, when knowing that enough is enough. Every now and again I receive emails from clients asking me to make the speech more emotional, and that presents a few problems.
The first one is - you're almost certainly going to fall into the trap of saying the same thing in a few different ways, and that gets pretty boring pretty quickly. Nothing lessens the impact of a statement than repeating it, it's always a case of diminishing returns. The second one is, you're just adding pointlessly to the length of the speech with the sole remit of guests thinking about how wonderfully moving and in tune with your feelings you are. This speech is about your daughter, and you need to celebrate her in the most efficient way possible; there are no prizes for talking any longer than necessary.
So, yes by all means have an emotional speech, but make sure you balance it out with humour, don't let those emotive lines bloat the speech, and whatever you do don't repeat yourself. If something feels like you've heard before in the speech, then it's best left out.