We weeded out luggage and only kept the pieces we really liked and use most often.
I nest the airplane travel luggage in the largest suitcase (hard-sided with excellent wheels), which includes backpacks and a rolling carry-on and the medium size version of the large suitcase. We typically travel with one checked suitcase (total, not each) and a backpack each on the plane. Our last vacation was ten days in Hawaii and we brought three backpacks, one booster seat, and one rolling carry-on bag -- no checked bags at all. Made me feel a lot better about ditching most of our luggage.

DH travels for business a few times a year and uses the suitcases.
I nest the car travel luggage in the largest rolling duffle bag (lots of pockets, sturdy wheels and handles, squishable for cramming into vehicles). This set includes gym bags and soft-sided briefcases and a smaller rolling duffle bag and smaller luggage-style tote bags. Although, I haven't dug around in here for awhile and wonder if I donated most of this...
I have a large zip-top fabric bag where I put all the other zippered bags (all sizes). This includes toiletry bags, cosmetic bags (small), garment bags (simple ones), shoe pouches (open-end jersey knit pocket for stowing shoes with clothing without leaving marks), beach bags (during our off-season), etc. We get into this bag throughout the year and swap stuff all the time.
All three main pieces fit neatly in a square space in our master closet under DH's hanging clothes between the three-bin laundry sorter and DH's shoe basket. The airplane suitcase slides in sideways and rolls out of the way in order to access the other pieces from one side. Or, the laundry sorter can be rolled out of the closet for easy-access to the other pieces from that side. It is an awkward spot to store anything and this is the best use, yet, and has been like this for about two years now. The fabric bag can be accessed easily from either side if you just want to reach in and grab something or put something away quickly, which is great. If you need to literally lift it up and empty it out, then it requires moving something out of the way first.