I can vouch for AER amps as a good solution. I have an AER Alpha which I use for background gigs and it serves me well. I had a comment just the other day from a wedding guest who was blown away by how natural the amp sounded.
Personally I think there is room for a little improvement with the sound. The duel piezo pickup (treble/bass side) going straight into my amp can sound a little 'punchy' at times and therefore not as natural sounding as I would like. The amp is also very directional, although this is true of most. With the AER you get a very airy, treble quality when listening to it from directly in front, however if you are just fractionally to the side of the amp the treble disappears along with any hiss etc. This means that 90% of your audience get a lovely, warm, thick sound whereas the 10% who are directly in front get punched in the face with piezo quack mixed with a little speaker hiss (depending on how close they are sitting. At a distance there is no issue at all). That being said I would still recommend the amp. I think that the majority of the audience at a wedding aren't too picky about the sound, it's really just a personal thing for us guitarists. Just be careful about how loud you crank the amp when you're close to the audience.
I've heard good things recently about the Carlos Juan pickup systems and Acoustic Image amps. I've not used them personally but I have it on good authority that these are superb solutions to amplifying the classical guitar. I've also heard great things about the Acus amps however I haven't had chance to test these with a classical guitar.