I think most of the kitchen design that I do and teach is that most good design comes from the people it is being designed for. You and your husband both probably have good reasons for wanting either choice so I’ll just give you some general rules I use to help guide my customers.
1. What is the height of the users?
2. Are we going to have cooking (hot surfaces) on the island?
3. Will the space be used for food preparation?
4. Will you layout buffet style food on special occasions?
5. Does anyone that might use them have any ailments that could limit them?
6. Do you have a dog that can steal food from your counters?
These are just a few questions to ask yourselves that might help guide you to your best layout. As for my 2 cents, most times a single level island is a more user friendly set up in general. It offers larger uninterrupted space, easier for kids and seems to allow everyone to use all 4 sides better. You need to work with a good designer that listens to the needs of their customer and helps guide them.