What are pros/cons of skylight placement?
I think you've figured out the pros/cons already: solar gain and light brightness. 

I'd place them on both sides for symmetry, but without seeing the room, that's just a random thought.

A pet peeve of mine is cheap skylights, though. If you're going to invest in these, consider doing it right and get a model that:


can be opened (a easy way to help cool the house in summer)
can be opened remotely (you want powered windows)
has some form of shades/blinds


Nice to haves:


rain detection (will close for you if it detects rain)
internal power shades (to 'soften' direct light)
external power black-out shutters (for when you want full sun blocked)