Visitors come to see, experience, and discover all sorts of things, so open spaces, with high ceilings and large walkable paths, which can host a lot of people are important. Lighting is key as well ; leveraging natural and artificial lights to highlight what needs to be highlighted. Because exhibitions usually require a few hours of visit, the space should feel comfortable, which makes lighting important once again but also ventilation. Finally, I think innovative and original designs make great exhibition space because there is a discovery aspect in the building architecture itself. This includes exterior facades and landscaping, which draw the attention to the building, and continues inside when there are interesting approaches to space, with different levels, perspectives, and views.
A museum I really want to go to is the Louvres in Abu Dhabi, UAE because of the building architecture, its open spaces, and how it is open to the sea. The Louis Vuitton Foundation is also a great place, with a lot of natural light in the lobby and hallways but artificial light close in the exhibition rooms, and overall nice exterior facade and landscaping.