I guess it depends on how big you want the suitcases. For 7 nights, I usually cram it in a 21" carry on. For longer, I use something like this
https://www.walmart.com/ip/iFLY-Hardside-Fibertech-Luggage-28-Checked-Luggage-Rose-Gold/275777816.
It's max size for checked baggage, fits under the bed, holds up pretty well and is relatively cheap.
However, you don't want too many in your room as they are large.