Looking through catalogs, I see pictures of lilac bushes in full bloom with sunflowers blooming nearby, illustrating how well they rebloom during the season. If I bought one, should I expect that or should I expect them to be like my reblooming day lilies, and bloom once in spring and have a few dotty reblooms through the summer?
I don't have first-hand experience with either of these varieties, but reading around suggest that they can, under the right circumstances, perform as well as advertised. Thanks for asking, as it's given me something to suggest to my wife that we add to the garden in the next year!
This site suggests that Bloomerang appears a bit more tolerant of warmer climates, but that cooler climates like the Pacific NW or up into Canada are good for the Josee lilacs (you basically need a more cool summer time).
The thread at http://forums2.gardenweb.com/forums/load/shrubs/msg1208520114000.html?31 adds weight to the suggestion that these are for the zones with cooler summers, as those saying they both varieties show locations in zones 4-7a.
Re-blooming Daylilies? The best Daylily I know is Stella d'Oro. It'll bloom continuously IF YOU REMOVE THE OLD FLOWERS before they go to seed. All plants want to reproduce themselves, especially annuals. Take the flowers off, the sooner the better and all the energy going into those flowers goes back to the plant making it bigger, more vigorous and producing even more flowers. This has to be done daily as daylily means just that, a flower blooms for just one day. If you don't take the flowers off each day the plant is into making seed. Once they've made seed they relax. They've done their job.
From what I've seen, lilacs do well (flowering profusely the next year) if you cut the flowers off, prune out old wood (careful with pruning too much), fertilize lightly with lower nitrogen and make sure the pH is closer to 7 (more alkaline). They like the pH of a lawn and more often than not they are in close proximity to a lawn which gets fertilized with high nitrogen. Thus few blooms. The reblooming lilacs I've seen do set out new buds and do pretty well if you've cut the other flowers off. I've seen them bloom all summer through late summer, but not profusely.
Personally, I am a foliage person. Flowers are like the cherry on a sundae. Thrilling each and every one! But if the foliage isn't healthy there is no background on which to display the flowers. Lots of flowers, to me, mean lots more work. Lush foliage can be better than flowers...