Great question.
Thankfully, at least the keyboard has the garage to slide into to protect it when not in use. But for the rest of it...
This may seem extreme, but for my retro-room (which is in my basement) I actually used blue painter's tape and blocked out all UV sunlight from the exterior window. Thankfully my window is rather small. A little light can still enter the room a little through my door, though, which is frosted glass. But I do my best to minimize it.
Most of my 8-bits (including my Vectrex) have custom made black vinyl covers made by a great lady in Texas. She even has the logos stitched onto the things, which looks great.
But that doesn't include the old monitors.
What someone on Twitter encouraged me to get a few months ago was
one of these. It fits a 15" monitor which should be close enough.
That doesn't do anything for the entire machine and drive on the side, but it's a good start (without just throwing a towel over everything; looking at these machines is half the fun).