I love White Innocence too, and grow one of mine amongst Cotinus 'Grace' though this year I will either have to prune Grace or move W.I.
Not a very good pic but the peony at the front of W I is Circus Circus and you can see how much taller W I is!
For single whites I agree with Nick & Alex - hard to beat Krinkled White but I also love Claire de Lune and while it is strictly speaking a semi-double, Nicola is a good one.
