Ah, great question! The biggest thing to note is that a day-of wedding coordinator won't be involved in wedding design or recommend vendors like a full-service wedding planner would. Instead, a day-of coordinator typically comes on board in the month leading up to your wedding, focusing on logistics and organization, fine-tuning your timeline, jumping in with vendor communication when needed, etc.
1. You don't want to end up working on your wedding day.
No matter how on top of it you are, you don't want to be the one organizing vendor setup and tear-down on your wedding day. You'll need someone who knows design well (they'll need to tell your vendors where and how to place those rental items or florals), who is willing to show up hours early and is willing to stand in the corner of the reception space and manage bartenders, caterers, and speeches...and who is willing to stay long after everyone leaves to manage the vendor tear-down process as well. It's just not a job you want to stick any of your wedding party or family members with, as it leaves them no time to actually enjoy the celebration. Plus, you need someone with a specific skillset who can put out last-minute fires, rearrange seating at the eleventh hour if need be, throw together a forgotten place-card at the last minute, stay on top of the timeline, direct your wedding party, and more. (It's exhausting just thinking about all of those things!)
2. There are lots of loose ends to tie up in the 30 days before your wedding.
First off, kudos to you for those incredible organization skills! You've made it this far without a professional coordinator—but the month before your wedding can be, by far, the most stressful. This is when you're collecting the last of RSVPs, tweaking your seating chart, confirming vendors, etc. It can turn even the most cool, calm, and collected bride or groom into a frazzled (and forgetful) mess who's bound to let a few important details slip through the cracks. There's nothing like the peace of mind that comes along with getting to hand those overwhelming details over to a coordinator and spend the month leading up to your wedding focusing on what's actually important: you and your spouse to be!
3. You need someone to make sure your ceremony & reception goes smoothly.
Ceremony mistakes are common—and, unfortunately, they're often the most cringe-worthy. A day-of coordinator will be there for your ceremony rehearsal to run through things with your wedding party and ensure everyone knows where they need to be and when. They will also be there on the day-of, directing guest traffic, corralling your wedding party, fixing the groom's crooked boutonniere, providing copies of your vows to your officiant, and making sure you're tucked away and kept out of guests' sites all the while. Even with family members or friends helping, there's really no way to ensure a smooth, seamless ceremony without a professional coordinator on-hand playing figurative Tetris with all of the many moving parts that go into a successful wedding ceremony. Besides, you want your family & friends to enjoy your wedding as a guest, not stressed out worrying about a timeline right?