The simple answer to your question is: no, the Infinity P363, while very good speakers for their price, are a completely inappropriate choice for a large, 200 person wedding.
It seems as though you're dead set on them anyway, so I'm guessing that all you really wanted was to get a "thumbs up". If there's no changing your mind away from your plan, then by all means, go for it. But be warned, you're not going to get what you want in terms of sound quality, quantity, coverage or evenness. With all of those caveats mentioned, if that's what you want, have at it!
There seems to be a fundamental misunderstanding on both your part and on the part of your fiance as to how sound works. If you or she hates the normal "concert" type setup - where you have big PA speakers up on the stage that are deafening when you're close to the stage, but pleasant if you're at the far end of the room - I can totally understand that. Sound gets weaker as you move farther away, so the only way that conventional speakers can "fill the room" is to play very, very loud. That's a problem for anyone who is standing close to those speakers!
Thankfully, line array speakers have been developed. Most inexpensive DJs are not going to have line array speakers. But if you search around, you might be able to find a company that uses them.
You'll find line array speakers being used at large, outdoor concerts these days. Line arrays can basically be "aimed", almost like a lazer of sound, rather than just a big old horn shooting out from the stage. Line arrays get mounted up high and aimed to cover the portion of the audience that is far away from the stage. Regular speakers on the stage are used for the front half of the audience closest to the stage - but they no longer have to play nearly as loud as the old concerts used to. They no longer have to project sound all the way to the back half of the audience, so they don't have to be nearly as loud. Instead, the line array mounted up high covers the back half of the audience.
So search around and see if you can find a DJ or concert company that uses line array speakers so that the stage speakers don't have to be so loud, but you still get nice, even coverage of sound for the entire venue.
If you're dead set on doing it yourself, then what you really want are the
CBT36 Line Array speakers that you buy in the form of a kit that you put together yourself. These are utterly unique speakers that essentially sound the same no matter where you are in the room. Whether you're right up close to them or all the way in the back corner, the sound stays almost exactly the same in both quality and volume. It's a truly unique speaker design that is perfect for a situation like yours.
They're $2000 for the kit though, and you need 4 amplifiers (2 amps for each speaker). Plus you need a DSP processor that can act as the cross-over, since the tweeters and the woofers are driven independently. Luckily, Onkyo has started selling receivers that include a manually controlled digital cross-over option that is perfect for these speakers. The $1000 TX-NR818 is the first receiver available with this functionality, although its own, built-in amplifiers might not be powerful enough for the room size and the CBT36's 4 ohm load. You can use separate amps if the TX-NR818 is not sufficient on its own.
The CBT36 are also not really meant for very low bass. They're good down to around 60Hz, maybe 50Hz - although not in such a large room setting. So if you want some good dance beats, you'll want to add at least one subwoofer as well, probably a pair of subwoofers.
Honestly, though, if you were looking at the Infinity P363, I have to assume your budget is quite low. Honestly, the easiest and best way to handle something like a 200 person wedding is to hire a professional. See if you can find one who uses line array speakers - although I honestly think that's rather unlikely if your budget is around what the P363 speakers and a receiver to drive them costs. Instead, find a pro who is willing to work with you on getting the volume level to a place that your finace is happy with - and find someone who has the equipment to mount the speakers way up high so that they can fire above the gathering and work to better "blanket" the audience, rather than firing straight out at everyone from ear level on the stage.
I'm guessing this is not what you wanted to hear, based on your previous reply. But I would hope that you're more concerned with making your fiance happy and having good sound at the wedding than with merely trying to force your own idea of the P363 speakers to work when they really are not appropriate for this purpose. They're good speakers, but they're just not meant for this sort of thing. Not at all.
