Andrea, just saw your post and have used several balloon flowers over the years.
As Lorraine, I do like 'Hakone Blue'.
For me at least, there's a problem with the dwarf ones (e.g. Sentimental Blue'). Pictures below, the same plant before and after I'd deadheaded it.
I may be a bit of a perfectionist, but, personally, I don't like the look of that concentration of spent blooms. I even deadhead the regular-sized ones.
Also, you read about the longevity of balloon flowers (and other perennials!), but I assume that's really only when they're grown in excellent, if not ideal, growing conditions. Their longtime survival rate in my packed perennial beds is usually not many years, though a few have lasted longer. Below balloon flowers at Merlin's Hollow, which were planted 20 to 30 years before the picture was taken. These certainly have the sun and the drainage (re latter, the path is made of crushed stone).
