FTD looks like the winner so far, offering 20 United miles per dollar spent or 15 American miles per dollar spent.
On the whole FTD is pretty reliable. Not as good as Proflowers.com but better than 1-800-Flowers.
I’d rather earn Starwood points for my flowers orders, but 10 Starwood points per dollar from 1-800-Flowers (with the bonus 200 points per order having expired) just isn’t the best offer. But if 1-800-Flowers would offer 100 Delta miles per dollar again I’d sure order fast from them!
Earning miles for flowers isn’t the only option. Points.com also offers the ability to burn miles in exchange for flowers.