I would want a volleyball net for the purple ball and some other fun activities like that. Maybe a forklift?
I would totally add a library. I think this is a great way to make Grimoire cards accessible in-game. There could be a database where we could enter the data we learned in the field to help an Archivist accumulate knowledge on our enemies and push back the Darkness. It would be even sweeter if, as our Grimoire score increased, we could also increase our Archivist Level, which would eventually allow use to purchase sweet class items and emblems, something to represent our love for the lore of the game. It would be a fantastic place for people to chill, and touch up on their knowledge of the Destiny universe.