Because my old stuff still works well and and I don't want to swap it out I am riding a double. But my wife went from a double to a triple and she will never go back.

Others have given a lot of great advice, but here is one more... if you don't want a triple don't shift into the granny and save yourself some money.

Actually there is some truth in setting up the gearing on your bike as a double and then only use the granny when you have to. Swap out the cassette, maybe change the chainrings and, if you have enough latitude, adjust the chainline. You can still leave the granny on there, and have a very minor weight penalty. Then don't shift into it unless you really need it.

John