welcome to the dis & congrats on your upcoming wedding!
the firework cruises are amazing, me & my fiance have done 2. they run about $140 & you can add appetizers, dessert & drinks from the resort catering/room service.
unfortunatly the fireworks cruise from the yacht club & epcot area can only accomodate 10 guests on a pontoon & only 7 guests on the breathless. unless you got very lucky & got 2 boats it wouldnt be doable for your size group. another option is the grand1 yacht from the grand floridian resort which views the magic kingdom fireworks & accomodates 16. 407-wdw-play to reserve (within 90days) a firework cruise & get more info.
best of luck.