Originally Posted by
highlanderfil
Personal reasons - I won't know the dates of my return flight for a while and I need to buy my first ticket very soon.
Well, for many tickets you'll be able to change the return date by paying the change fee + fare difference. In some cases just the change fee if there is availability in the same fare class. I would just buy one of the RT tickets with a date that's close to the one you need and then change it if you need to later.