I'm just starting to plan out my signals, I expect to have quite a few. I have to draw a full schematic of the layout first to figure out how many I will need. There will be single, double and triple heads as necessary.
A while back I picked up 100 searchlight style targets, that take a 5mm LED. I got the targets from WeHonest out of China on eBay. I'll have to make my own masts, ladders and platforms for them. When a bridge is called for, the old 450 isn't a bad structure. I'll just make my custom heads for them. I also bought some dwarfs from WeHonest. That package should be here next week. Speak of the devil, they just showed up in today's mail. They look nice too.
Controlling all this will be the JMRI software and C/MRI hardware. I have all the C/MRI outputs I need, but I have to get the accessory signal driver cards. Those will turn a regular red/green LED into red/yellow/green by using AC on the red and green to make it look yellow. The driver card has a trim pot so you can adjust the flicker rate to favor the red, giving you a more prototypical amber color.
These won't go into service for at least a year, maybe two, but I am thinking about it pretty seriously now, so I'm ready when I get to that point.