I did gift bags for every room with mostly the same things included. They all included soda, snacks, a few gifty-souvenirs, Advil, Band-Aids, sunscreen and bug wipes, tissues, Disney candy, Cinderella pens, Cinderella or Mickey lip balm, a dollar-store umbrella that I personalized with our names and the date, just in case and possibly more... they were full!
I did personalize the contants of some of the bags, depending on who was getting them. For instance, for my MOH's daughter I included a Cinderella coloring book and crayons, for my Dad whose name is Donald I included a lanyard full of Doanld Duck pins, and for the moms I included special tissues I had found that said, "Because I'm the mom, that's why!"
I saved the bridal party and parent gifts for the reception and gave them as going-away presents, without putting them on the spot in front of the whole group. I was able to do this, though, because their gifts were not necessary for the wedding (no bridal party jewelry, for example.)
One thing I found to be indispensible was to get bags that zipped across the top - I bought them in wholesale lots on eBay - so that each bag was closed when they received it. Since most of the special items were obviously intended for one person, no one opened them together or found a need to compare.
I will add that my gift bags were really expensive and I'm sure a lot of snacks and things got left in the room, so I'd definitely downsize if I did it all again!
