My daughter is a Junior in college and she lives about 20 minutes away in her own (our) condo.
As a child, she had the entire upstairs of my house to herself... 3 bedrooms, 2 bath, library and game room. So she had her things everywhere.
When she moved, she took most of the furniture from upstairs so her old bedroom only has the vanity that would not work in the condo. Clothes that she wanted to store, are in her closet... prom gowns, etc. Another closet is the cheer closet with all the cheer gear, and then a closet with all the martial arts gear (she is a black belt) so we have a lot of equipment for martial arts as well.
Since my upstairs is pretty much empty now, with exception of the game room with pool table and guest room that has been redone, I have most of her things in closets. She comes over about once a week and sometimes we go through things and she designates what gets donated and I take it to Goodwill.
The rest of the things, including toys, books, games, etc will wait for her to go through when she wants and decide what she wants to keep or donate.
It is not an issue because I have the extra space to store her things.
When I graduated from college, my mom stored most of my things and I am slowly getting things back. On my last visit, she gave me all the albums I had as a teen and some other momentos.
Isn't it fun being empty nester? I LOVED every stage with my daughter and right now I LOVE the stage we are in because we are so close.