Should my wife and I buy the expansion?

[Aeyis]

oh yea once thing i will say, you can't pass lvl 50 without the expansion, the lvl 50 quests give players who have the expansion exp. so if you get to lvl 50 you would want to buy it for the extra exp to help lvl you up a bit before reaching 3.0 content.

Heavensward doesnt need to be purchased for the changes to 2.0 content.

@OP:
I would wait and see if the game holds your interest. None of the Heavensward only content can be accessed before level 50 (and the level 50 main scenario quests) anyway.