This is a very timely topic as I just came back from a destination wedding that I'd been planning for 1.5 years with my fabulous couple.
When they first hired me, they were planning a local wedding and then things changed course a few months into the planning process and they decided to go with a destination wedding in the Caribbean. It was at this point, they questioned the need for me to continue on considering the resort was offering them a co-ordinator.
Thankfully for me, and them, they decided too and it was one of the best decisions they made (I'm sure they will attest to this).
You hire a planner for a local wedding, so why wouldn't you need one for a destination wedding? The co-ordinators that are available at the resort are looking after multiple weddings. Most resorts host up to 5 weddings per day, so on that important day, you don't have the co-ordinator 100% of the time. If something goes wrong, who do you call?
Remember, the planning of the actual "day" is only one aspect of the planning process. What about everything else that falls outside of that? Like establishing a realistic budget and managing it; looking for a gown; looking for the attendants outfits; purchasing the favors; etc...this is where your wedding planner helps you. A good planner should provide a wealth of knowledge and information on where to source things and steer you away from pitfalls. The resort co-ordinator will not help with this.
Now, let's touch on the value of them planning the wedding in conjunction with the co-ordinator. I would say that I exchanged at minimum, 100 emails with the resort co-ordinator. Planning a wedding takes alot of time especially if you want things done correctly. Once I understood the couples vision, I was able to work directly with the resort to bring it to life. The couple was only involved when it came time to make a decision - this is the way it should be. I also worked with the co-ordinator to make sure my client was getting the best deal, which included putting together several package options for the client to choose from.
Now that we have the wedding planned, this is where the rubber hits the road.
For this wedding, I met with the co-ordinator the day before the wedding to go through all the details one last time. This resort does not conduct wedding rehearsals - so I had to do that. I had to gather the entire bridal party and we went through the rehearsal a few times to make sure everyone understood the flow of the day. It's a good thing we did, because it allowed us to iron out some minor kinks.
On the day of the wedding, guess who was called when the following was needed:
a sewing kit because the flower came loose on the brides dress
we need to locate the photographer
we need to locate the parents to deal with an urgent matter
the wrong song was playing as the bridal party exited the gazebo
the food is taking too long to be served
a decision on if we should we take off the flood lights at the beach reception
moving the centerpieces from the dinner to the reception tables (the resort wouldn't do this)
arranging the seating plan
And just providing general support to the couple that day - it was me, the wedding planner and I loved every minute of it.
We (resort co-ordinator & I) made a great team in working together to make sure the day went off flawlessly. The guests had a great time and the bride and groom couldn't say "thank you" enough.
In summary, the resort co-ordinator takes care of "the day" but your planner takes care of the entire wedding process and any post wedding details. Most people plan to get married only once in their life. Make sure it is your best day and little details don't end up ruining it. Your guests are paying alot of money to spend this time with you, so you want make sure the day is super special for them as well.