My reply to your final question is always: It has to have meaning for your future bride, or even better, meaning for you as a couple.
Is there a specific ride, land, restaurant or character that has special meaning to her/you as a couple?
The castle is beautiful, but also a very standard proposal place. I would only propose there if this is her/your favourite place. A proposal gets more meaning when it's tailored. If you have a special bench where you always relax during the day with an ice cream, people watch from there, and enjoy your day. Then that bench is something specific for just the two of you.
In my opinion, you can propose over doing the dishes, if that's something with a lot of memories.