IRIS USA 64-Drawer Screw Organizer, Made in USA, Storage Chest for Hardware, Screws, Nuts & Bolts, Garage Tools, Charms, Beads, Craft, Scrapbook & Hobby Supplies, Teacher Toolbox, Black

The IRIS USA units are great for Lego parts, with the metal frame being a big advantage over other all-plastic brands. They often go on sale, so it's worth keeping an eye out for that. I admit that for many of the drawers I have made custom 3D-printed interior cups so I can divide the smaller pieces into color groups (candle parts for example), size groups (Bars in 3L, or 5L for instance), or other similar-type small pieces. IMO, they are better than the Akro-Mils but I guess there are fans for each brand out there. ETA: Just got delivery of a new, smaller IRIS unit (26 drawer version) and the outer frame is still metal. The rest is plastic, but the metal frame does help with overall rigidity. All of mine are on shelves, so no idea if that helps with wall-mounting them or not.

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.