Pacific Giants tend to be leggy.

Try English Delphiniums! You can get seed by joining the English Delphinium Society, or from Dowdeswell Delphiniums.

If you thin your plants to 3 shoots in the spring you will put more energy into the remaining three shoots you may get better, moree floriferous plants. For more information go to English Delphiniums, Alaskan Style!

Here is a link that might be useful: English Delphiniums, Alaskan Style

I'm trying delphs for the first time this year. I ordered from Graceful Gardens. I've purchased from them before and their plants were great, so I'm hoping to do okay with the delphs. Here's their address:
http://www.gracefulgardens.com/delphgrow.htm

There's also a good discussion on the Antique Roses forum. The link is below.

Here is a link that might be useful: Delphs

I'm Zone 6 and my delphiniums bloomed from May through late November. They topped out at four feet. My fear is that their extravagant, constant blooming means they might be a one (summer) and done. I fear that they simply can't expend all that energy and then do it again. Of course, I kept cutting the blooms when they went to seed to keep them blooming.