I've not seen, or tried, three of the variegated garden phlox, mentioned by Susie, and only tried two of the others ('Shockwave' and 'Harlequin') quite recently. But I've had a number of years using 'Becky Towe' and 'Nora Leigh'.
'Becky Towe' has never lasted more than three years for me, but 'Nora Leigh' has done exceptionally well. I have a number of 'Nora Leigh' plants (in several gardens) that have been going for, or for close to, ten years.
'Nora Leigh' is not a particularly vigorous grower and it's bloom is not very showy, but I find it blooms and looks attractive for an amazingly long period of time. Because it is so mildew resistant, I find it unnecessary to cut the foliage of 'Nora Leigh' down until mid or later October. Hence of all the several dozen or so different phlox cultivars in our garden, it has been the last one left standing.
Example: the same plant below.
(July 22, 2013)
(October 15, 2013)
There not much left standing and with bloom on it, in our garden, in mid October.
Below also October 15, 2013.
The most obvious colour below is the Arend's monkshood, the 'Firetail' Persicaria and the variegate 'Nora Leigh' (one of our three).
There is a small variegated 'Shockwave' in front of the monkshood, but it was only planted in the previous year.
