IRIS USA Plastic Drawer Storage Organizer Rolling Cart, with Wheels Casters, 5-Drawers, for Classroom Art Craft Supplies Dresser Closet Bathroom Laundry Room, Flat Smooth Top, White/Clear

Your post doesn't say whether your dilemma is organizing individual parts/pieces/minifigs, or if you want help with displaying your completed sets. Or perhaps both! Your Lego den seems to have a lot of wall space. Consider using Ikea Billy bookcases or some other 3rd party inexpensive shelving all around the perimeter of the room to display your completed items. The Billys have glass doors you could add later on to help protect your sets from dust. You could designate one (or two or three... etc.) of those shelving units for, say, the Harry Potter universe sets; another for various vehicles, including trucks, autos, pickups, etc.; a set of shelves for the City and/or Modular building sets, and so on. It depends in part on how *you* think about your collection and the groups that make sense to you. When it comes to parts, I think you will be well served by a combination of IRIS-type storage units in various configurations depending on how many types of small parts you own. These fit in Billy bookcases really well, but shallower options are available that also work. Add some Alexa drawer units for things like build plates or use the cheaper plastic drawer units if you are trying to keep costs down. There are lots of inexpensive drawer options out there. Finally, take a look at Tom Alphin's site and the labels he produces. That should help you get started. Good luck! It's a continually evolving task which I have found is never completely finished.