What to do with empty rooms?

Exercise stations, music room, meditation (needs the least amount of furniture), storage.

Reading room or study room

@Chikipi: Good idea. Add book cases and make it a library.

Library or maybe a “wine cellar”.

Art gallery or plant room ( Think greenhouse ).

Computer or entertainment room

Home gym for one, Media room for another (TV, music etc) and wine cellar/ library for the third.

You can combine art, plants, books, media, comfy chair,and good lights in one room and have it all (except for the rowing machine).

Use them for storage, maybe as s walk-in closet, game room, music room, library/reading room. In my old house, we had a random, walk-in closet (at least not big enough to be another room) that my family used to store books and board games. There was at least three, 6 feet tall shelves in there and a small couch. :)
How small are these rooms?

Oh, how I long for a little workspace of my own! Does everyone have his own office/workspace? It’s really nice to have a separate study and work space from your bedroom, where relaxation and intimate encounters are supposed to happen.

I’d definitely have a library/study if I had an extra room – probably just a desk, bookshelves and plants.

The second I’d make one a crazy jungle gym thing for my cat, with structures she could climb all over… I’m always afraid she gets bored while I’m at work.

As for the third, get a baby gate for the door and just fill the room with those plastic balls. BALL PIT!!!

I have a treadmill in an extra room and I love having it, especially when it is FREEZING cold outside like it is today. I also have a home office as some have suggested above.

If your clothes are tight in your closet you could make a fabulous dressing room. In the center you could have a folding table or low dresser where you can fold items and put in a three-way mirror, bars for hanging clothes, and shelves for sweaters, etc. You could go shopping in your closet every day.

A home office! A library! A music room! ‘Twould be heaven if I had those!

Fill them with balloons

@RareDenver I like that idea. Just walk in and shut the door behind you. Balloon bliss. :P

Reading room and if they are a Couple get some Mattresses for each room and Decorate with lights and have a Theme and then change rooms when your feeling Randy…

@phil196662 I used to work with a woman named Randy. I had a vendor who used to visit once a month and he was British, he told me one day that he had the hardest time calling her Randy.

That is a Good One! @Jleslie – I gues we will never know if she was True to her name…lol

They could rent one out!!! and make some money. Aside from that me personally I’d like a meditation room, with beautiful pictures on the walls soft music and good reading, candles you know. Another one could be a study and another one just a spare room when you fancy a change of sleeping scenery :)

Hide the bodies.

How about a meth lab and/or grown room? :)

On a serious note, make one a guest room, and use the others for art spaces

I put more exercise equipment in there and I use it all the time. An extra TV and ironing board .

My extra room is the cat’s room. Got any pets?

Take the darkest of them and store all your sad memories, regrets and guilty feelings in there. Keep the door closed.

Make one into a guest room with a single bed so that when friends crash at your place, they’re not on your couch.
Put shelves in one for storage of bigger stuff, like luggage, bicycles, skis, musical equipment, computer boxes, etc. as well as extra supplies, like TP, paper towels, etc. that are cheaper purchased in bulk but take up room.
Put a desk, bookcases and a comfy chair in one, so that there’s a place to get away from common space without having to be in a bedroom.