Kudos to you for your decision. I am all for letting people do things for me that I don't have time to do myself.
I just let my DH convince me not to paint our kitchen myself. This was a big decision for me because I actually like to paint and I'm good at it. I also wanted to try a painting technique that I have in my head how I'd accomplish it, but I don't know that anyone else would be able to get it to look the way I wanted it. I'll just have straight paint on the walls for now. Maybe someday, there will be more than 24 hours in a day so I can do what I want to do, what I like to do, and what I have to do. So far the "have to's" are winning.
Your party will be lovely, I'm sure, and with no stress on you.