Judy--

I'm by no means an hydrangea expert, but I'm fairly certain that Nikko Blues bloom on old wood. Endless Summers bloom on new wood, so you should be good there. The hydrangea forum here is great, and I bet you could run a search and find out about the limelights, bluebird, pee gees, etc.

I'm in the market for a bluebird... has it bloomed well for you?

It's realy too soon to take anything from my experience as the norm with the bluebird. I bought it the end of summer 2005, moved it last spring to a shadier spot. It produced a about 4 flowers, last summer. It's not really had time to establish itself.

Nikko blooms on old wood and Endless Summer (and probably Everblooming -haven't heard of that one) blooms on old and new wood. I don't know abouth the others...
With all the pruning warnings about hydrangeas, I think the best course is to prune in the summer after the first flush of blooms and let it go - that way, you are assured of the best chances for heavy blooms - if the late frosts don't kill all your buds (keeping fingers crossed this year!)

Zack