re: Two Galaxies
M31 is a great object to show (the furthest thing visible with the naked eye)!
But then, we have our binoculars and it shows better that way.
Luckily, there's the W from Cassiopeia; I'd point to Shedar, ask the visitor to recognize Mirach in the Andromeda constellation (both are visible without binoculars) and ask him to draw an imaginary line from Shedar towards the Andromeda constellation and another one up from Mirach, then Mu Andromedae and the intersection is M31!
From Starry Night