It'd be great to have a space that shares audio and video from the collection and gives customers the chance to share their own.
The Special Collections departments should have a meeting room/classroom space for its own events.
There should be small exhibit areas and display space to show off interesting and important items in the collection, especially since the contents of the collections are not always accessible.
There should be a welcome desk to direct customers and answer questions.
Study tables and chairs with sufficient space to spread out larger items like maps, newspapers, atlases, etc. is important.