I love floribunda wisterias but so far have been unsuccessful with them (in Sonoma).
Nevertheless, I just purchased a double-flowering plant from a dealer on ebay. It's small- only about 17"+/- and very slight. Hoping it blooms in my lifetime! ;) My last attempt at a Japanese floribunda wisteria (alba longissima) was over a decade's worth of hope and failure. I had it in a wine-barrel and evidently it was never content enough to bloom. I think I bought it as a 3 gal (maybe even 5) back in the mid-late 90s. I don't know how to get them to bloom in containers (I saw them recommended for containers). I clearly haven't got it right. Meanwhile I am nursing cuttings of a dwarf wisteria Wisteria sinensis 'Kofuji' that I took this last winter (when I pruned my main plant which is still in a 3 gal.) which are just leafing out. Hoping they make it. I can not seem to find a photo of the plant in bloom, even on nursery websites who sell it. Ideal for bonsai with it's tiny leaves but I'm skeptical of the success in getting it to bloom.