I want to start by saying our photographer was AMAZING! I love lots of the photos (900+ pics, you're not going to love them all) She asked for a list, which I'd prepared even before she asked after reading all the "give them a list" topics. I love our photos and will have beautiful wall photos in our new house, a wonderful album when we choose our favourites (self made, we paid for all pics but digital format only) and fantastic memories from the rest.
However, there are photos we didn't get which I wish we had, or had more of. This lies with us and not the photog, as she sent a form to be completed. It really does come down to something you'd regard as obvious or not occur to you when completing the form. I kept thinking afterwards "why would I have thought of mentioning that when it's standard?!" but of course, no two families are the same!
So, My point is, as other have said, list EVERY detail, EVERY person/group, EVERY scene or scenario for photos that you would like.
As I said, My pics are amazing but the ones of my camera shy mum and me are awkward, I'd have like a couple more where by which point she might have felt at ease. I also have none of just my son and daughter. I didn't request them, didn't occur to me, but looking through I really wish I had them (he was with H getting ready and she was with me so we met at the Church and have the 4 of us or me and D but not me, S and D or just D and D)
Hope this helps and lots of luck to you all.