Fred and Mary have acquired some very interesting contemporary art and installed it in their home. I know contemporary art is not for everyone, but I do think some of what they have is very good. Don't know if they have an art consultant or not, but I would assume so.
Same counts for the Belgian king and queen. They installed some great contemporary artworks in the castle in Brussels. This is mostly Paola's merit. She's very into contemporary art. i doubt she has much official consulting. She has a friendship with the curator Jan Hoet though. I'm sure he advises her whom to explore more.
My favourite: the green beetle ceiling by Jan Fabre.