Well, you're right. I don't know what the hills are like where she's riding. And V., I would certainly not call that hill profile "moderate"! (That's why I load my response with caveats.) If that's a routine ride in her area, then a triple might be a viable option.
Here's a gearing chart where you can look at your gearing options. http://i1.net/~dwolfe/gerz/index.html
I think it's always good to have the numbers in front of you when you're making your decision. Look at the low end (and the high end) of your gearing options. Are you really losing anything? If you are losing more than you're comfortable with - then, sure - maybe it's worth it to opt for a bike with a triple. I think converting that bike to a triple might not be worth the added expense, when perhaps there are similar bikes in the Giant line that already have it. I don't know. I'm not familiar with their line (and haven't gone and researched it before posting this).
p.s. And yes, there was more to my rebuild than just the crank. There had to be to allow the bike to shift. And some of the rebuild was just bling.