I have almost 3 y/o b/g twins too. My daughter started showing interest around 2 or a little younger, then it totally waned. When she was 2 1/2, she just started going pee on the potty one weekend, with very few accidents since. Poop on the potty took a little longer--she's only been doing that for a month or two now.
We started out with two little potties on the floor, and wrote their names on them (at that age, they could recognize their first initial) and let them decorate them with stickers. We let them watch Elmo's Potty Time, and just asked them if they wanted to try to go potty. We use stickers for rewards--one for pee, two for pee and poop. Like I said, my daughter pretty much just decided one day that she would take to it and that was that. We focused on her since her interest was stronger, and we really didn't want to potty train them both at the same time. After she was used to the little potty, we got a seat for the toilet and now she's completely good to go, and normally doesn't even care about the sticker reward.
My son is still barely interested, and we don't push him. We ask him if he wants to go, and sometimes he does and sometimes he doesn't. Sometimes he gets really excited about it, other times he cries if we just ask him if he wants to try.
Keep up your attitude though! I think it's great that you're approaching it so relaxed. I am a firm believer that they will take to it when they're ready. 17 months is probably a little young, but you can start encouraging the interest, and ask her if she wants to try to go potty. I think those potty chairs sat in our bathroom for about 6 months before our daughter was really ready to do it!