Inspired by this thread I started using scanlines and took a few steps back from the monitor
I've got a PC with WinUAE and a 19" monitor and I used to sit right infront of the monitor. I changed my windows to a lower resolution and now I'm sitting on my bed, maybe about a meter and a half from the monitor. It feels like the scanlines look better here but when I get close to the monitor they get annoying.
Also gotta turn up the brightness a little bit when using scanlines 'cos the image gets a bit darker.