I think a lace cap in a complimentary color would be nice.

Yes, I thought lacecap too but I'm not sure which ones would be complementary, especially given QF's color changes. Any specific ideas? Thanks!

Oh yikes! That's actually a tough one with alkaline soil. I paired QF with ES, but with acidic soil, the blue was lovely with the many shades of QF. I don't think I'd want a pink hydrangea next to QF. The pretty pink of QF only lasts a short while, and the dull pink lasts too long IMO. Perhaps the green of Limelight would compliment QF?

Since QF goes through a lot of color changes I think a neutral would be best like white or green. I love the color of limelights as mehearty states but I think a limelight could upstage your QF. So I did a search for white lacecaps and came up with the following:

Lanarth
White wave
Princess lace (Monrovia.com)

You can google those for pics and ask your local nursery for suggestions too.

I have a Limelight next to my Quickfires. Limelight looks good with anything. My soil is 6.8
Cher