Hi Kate. I am planning on having our wedding at Gran/Royal. I like the idea of guests having the choice. I was thinking originally of my FI and I staying at the Royal and having the wedding there, and I know guests stay at Gran can come to the Royal without buying a day pass just for the wedding, and Royal guests can go to Gran without a day pass. My thing is that I want my bridesmaids, mother and future MIL to be able to be with me getting ready- and don't want them to purchase a day pass just to be with me in my room for the day. As of now I'm thinking of staying at Gran for the couple of nights prior to the wedding, having the wedding there, then wedding night and 3 nights following, my FI and I to tranfer to Royal.
That way we can be with everyone the day of the wedding, and still enjoy the luxurious rooms at Royal.
Not sure if thats something you have looked at but it sounds as of you can upgrade to Royal even once you get there and change your mind so that's a plus!! And I'm glad someone has been contiplating this Gran/Royal thing like I have for the past month! LOL
Happy planning!!