When my sister got married they allowed her to decorate the day previously so right after the rehearsal dinner my parents, aunts, cousins, and the bridal party decorated the entire hall. For her wedding we had to lay out the china and plates but mine is providing it. Hers also had a 300+ guest list.
For my wedding they are only allowing a 1 and a half to 2 hour window from 8-10 am to decorate and then after that no one is allowed inside until cocktail hour at 5. My mom doesn't want me to be involved in the decorating at all (my sister and her husband weren't allowed in until their wedding either) so that me and my FI will be surprised.
However, now my mom, and my sisters, who are really the only people I trust on this because they are bigger perfectionists then I am, will be with me getting around for the wedding. The only people available to decorate is maybe my father, my two aunts (one of whom has grandchildren to wrangle) and possibly my cousin. I just don't know if it's feasible. I only have a guest list of 150 so that may cut down on cost but I just don't see how it's possible.
We have our own centerpieces and although they will be almost ready then have one final thing that has to be added that same day and I'm concerned that it wouldn't work out.
I feel this is a ploy to get us to pay them to decorate but with the centerpieces they can't help.