Tiles are good on the bottom floor ... for a second floor, I would want to ancor them in some way ... if they can't go through the opening, they could still go part of the way down with the sharp corner aimed downward.
Also, as far as urine ... it could puddle on the tile, then roll down on another chin. You might consider a baking pan with 4 sides with the tile inside of the pan to control location and urine.
If the pan has a hole in the handles, it could easily be ancored to the second floor of the cage.
Ramps are where most chins get hurt ... a solid ramp is best ... if you use a ramp at all ... chinchillas usually jump from level to level with ease when there are no ramps. They are also good climbers on the walls of the cage.
Wood is good, but needs to be kept cleaned and replaced anytime there is a serious illness.
Cardboard is handy, cheap and disposable, but very messy when chewed in pieces and thrown from one end of the cage to the other. But, if you don't mind that ... Kleenex boxes (remove plastic first) make great hide-a-ways and chew toys.
NO regular PLASTICS, PLEASE!!!
4" or 5" PVC pipe is great for chins to play on, play in, hide in, sleep in, and are 100% safe and washable! You can buy the pipe and have it cut in 6 to 10" pieces or use the various "T", "Y" and other shapes that can be purchased. This is the only plastic that I know of that is safe for chinchillas.
(Take your check book ... the good stuff is not cheap.)
Jo Ann