Hi Ian,
I think double stars are a wonderful way to access observational astronomy and great fun as you say to think about and research. I’m sure you could master your 5″ refractor by focusing on the bright double stars (there are many) and then you’d be hooked. When conditions are less than ideal there are always beautiful double stars to fall back on and they can make great targets for little projects that help keep you engaged in this wonderful hobby. For example, a few years ago I decided to explore and image some of the double stars in Aries, my birth constellation. This was the result and it was great fun! Good luck 🙂
Hugh
