LED Strip Options for GSDS?

I have Glenn Snyder shelving, though I have not installed lighting on them.  I do have some (hopefully) helpful comments on your plan as I have experience with different types of LED strips.  

First, I wanted to clarify the LED strips you have selected.  These are individually addressable RGBW LEDs, meaning each LED includes a serial communication chip that allows it to be individually controlled to display millions of colors and brightness levels.  This requires either a dedicated pre-programmed controller box or use of an Arduino microprocessor or Raspberry Pi plus program code in order to light the LEDs.  Unlike conventional LED strips, simply connecting them to power will NOT light them.  This type of strip is commonly used for dramatic colorful dancing lighting effects.  

With these capabilities comes a price.  Your selected strips cost $2.68/foot, whereas conventional white or warm white 12 VDC LED strips can cost as little as $2.49 for 5 meters (16.4 feet).  You connect them to an appropriate power source and they light.  Note that there is a 3rd type of strip called RGB LED strips.  These also operate on 12 VDC and contain alternating Red, Blue, and Green LEDs along the length of the strip.  This is more of a Christmas tree light effect. A 4th type of strip is called COB lighting, which gives a continuous uniform light effect.

I like the idea of using the diffusers and mounting them at the edge of the shelf so they are shining back towards the trains being displayed.  The unknown is if they will actually illuminate the side vs. just the top of the trains.

I would suggest buying a single roll of warm white or bright white LED strips along with a cheap 12v, 2 amp wall wart power supply and experiment with placement to see if you like the lighting.  You and a friend could just hold the strip in place.  If you like the effect, then invest in a diffuser strip and mount them on a couple of shelves and re-evaluate before making the considerable investment in the whole project.

Since you will be buying in quantity, you may want to buy all your supplies from AliExpress.  The are an Asian counterpart to Amazon, and prices are far cheaper.  A 5 meter white LED light strip from Amazon runs $10-15, while you would only pay $2.49 (including shipping) at AliExpress.  

In selecting an LED light strip, you will need to decide on the color (warm white, bright white, blue, red, purple, etc.), the LED size (3528 is common, but there is also the larger 5050), LED density per 5 meters (150, 300, 600, or 1200 LEDs/5 meters), voltage (5V, 12V, or 24V) and waterproof vs non-waterproof.  The waterproof strips are encased in a clear rubbery silicone which also makes the strip stiffer and less prone to damage.  They are more costly than non-waterproof strips ($4.20/5 meter strip vs $2.39) but still quite inexpensive.

Personally, I would use 12v, 3528 size LEDs, 150 LEDs/5 Meters, waterproof.

You will need one or more beefier dimmable 12 VDC LED power supplies for all those lights such as this one available in 60 or 120 watt versions.  There are guides online to calculate power supply requirements, but a rough estimate is 2 amps or 24 watts for every 300 LEDs.  

Bob

This is great information, Bob! Thank you for taking the time to share, this definitely gives me a starting point. I'll test fit a couple different types of LEDs and diffuser placements to see how it looks, and I'll share pictures as I go.

On the controller front, I'm either going to use a WLED-capable controller or a Zigbee controller to connect these LEDs to the same home automation platform as the rest of the room.

I did dumb down my answer a bit, but clearly you have a handle on the WLEDs (addressable RGBW).  I have experience with these controlled from an Arduino but not from a dedicated controller or a Zigbee.  Post a link of the devices you are considering.

With Arduino control there is an issue of color shift in the LEDs farthest from the power supply.  I expect this would also occur with the controllers you will be using.  This is managed by adding additional power feeds along the strip.  In the case of your shelves, hopefully you can just parallel feed power to one end of each shelf and there won't be enough voltage loss to produce the color shift. Daisy chaining shelf to shelf to shelf probably will not work.  Keep us posted on your progress.

I love your passenger train collection!

Bob

Here's the WLED controller. I like it because it doesn't care what the voltage is, and it has two data pins to give a little bit of flexibility. WLED doesn't integrate directly with Google Home (yet), and since that's my primary means of interacting with most of my home automation, I'd have to find a workaround.

Here's the Zigbee controller. It's not quite as cool as WLED, but it will connect directly to the SmartThings hub I use for all the Zigbee and Z-Wave devices in the house, which means it'll integrate into Google Home seamlessly.

I got one of each, so I'll give it a shot.

I'm betting I'll have to inject power at the end of each of those long shelves, but might be able to daisy chain on some of the smaller one. I love looooong passenger trains more than just about anything, so those long shelves are great. I think I have two or three sets that are more than 17ft long, which is crazy.