So, my problem was two-fold:
I needed someplace to store all the freight cars I have (and capacity for all the cars I'd get in the future); and
I didn't want to use up a lot of space or spend a lot of money on turnouts by building big staging yards - and didn't think them very necessary since I'm only running two (for now) local freights.
Most folks just build the staging yards, but other alternatives include cassettes, shelves, or drawers. The biggest downside to these alternatives is the amount of equipment handling that's required (and the risk of damage) or, in the case of cassettes, having the same strings of cars being used over and over. Or even worse - you don't end up using the stored cars at all.
I wanted a solution that would protect my cars, minimize handling, and be easy to transport. I think I've found that solution in the "Seville Classics 10 Drawer Organizer."
For about $45 you get all you see here. It comes as a kit, so some assembly is required. But it goes together easy and quick. As you can see, I also added labels to the drawers to make things easy to find.
Each of the 10 drawers holds up to 12 HO scale (steam era) freight cars, for a whopping 120 car capacity. I lined the drawers with bubble wrap (the small bubbles, pointed up) to protect the cars from damage..
Using the cart for storage is pretty obvious and straightforward, but using it for offline staging is where it really shines, IMO. Since the cart is mounted on wheels, transporting all those cars around the layout is easy peasy. Based on the car orders my computer produces, I can quickly find the appropriate cars, and wheel the cart to where ever the cars need to go. This is really helpful for building trains before the session starts and for initially populating the layout with cars, if there aren't any already at the industries from a previous session. You can either pull out a car at a time, or pull out an entire drawer and place it on the top of the cart for easy & safe access to multiple cars at a time.
I can even just take one drawer at a time around the layout, if that's more convenient. But pulling out one drawer is especially helpful for when I want to safely transport a bunch of BO cars upstairs to the workbench.
The cart is pretty tall, so you'll want to be careful pushing it around (it'll flex a bit). And the wheels lock which is great when you don't want the cart to roll away or move on its own. But make sure the locks are off before you push it.
But those are the only points of concern I have - and even those are stretches. All in all, I've been very happy with this solution which addresses storage & staging at the same time.