Hope you mean joist, rafters are holding up the roof.
Any wood flooring would not be a great plan in any room where there's the potential of water damage.
A good quailty sheet linolium in a tile pattern could give you a nice look but be 100% water proof. Your going to need to add a layer of 1/4 subfloor rated underlaymant, making sure the seams do not line up with the seams below, no glue and fasten it every 4" on the edges and every 6 to 8"'s in the field.
I like to use a pneumatic narrow crown stapler, but it can be down with underlayment nails. If you go with nails you have to go back and fill all the nail holes. Both ways will need the seams filled and any flaws.
Once the walls and subfloor are already down there's not a whole lot you can do to make the room quieter.