The 'Endless Summer' type of hydrangea (Hydrangea macrophylla) is a plant that is best suited to a part shade location. They can be grown in full sun but will typically experience daily wilting in summer that will unnecessarily stress the plant, especially in areas that have hot summers. Even in the very mild and relatively cool summers of the PNW, shade is a recommended location for these. Hydrangea paniculata or arborescens are more adaptable to a full sun location, but these offer only white flowers. Specific plant selection is often something best left to locals.......issues like climatic suitability, soil conditions and potential invasivenss can come into play that are overlooked or unknown in such a wide forum. A visit to a good local garden center as the season progresses should help you with candidates for this situation, as would a visit to any local public gardens or arboreta. Purple-blue is a hard color to obtain from a flowering shrub and for a full sun location. Rose of Sharon is a possibility, as would be Caryopteris (aka blue mist spirea), but pink (even fuchsia or magenta) is a lot easier. Maybe focus on pink as flower color for the shrubs and accent with perennials or annuals - as suggested above - for the purple-blue color you seek. Hardy geranuims are a good source for this - very easy to grow, adaptable to a very wide range of growing conditions and and with a very long bloom season. Look for 'Rozanne', the 2008 Perenial Plant of the Year, and for good reason. If you include roses in your choices for pink/magenta flowers, hardy geraniums are one of the best companion plants.

For taller companions, you can use aruncus, cimicifuga and other hydrangeas, like H. Paniculata 'Limelight' or 'QuickFire.' For shorter ones, hostas and heucheras look great.

A couple of perennial recommendations: Purple Palace Heuchera: a good sized Heuchera, it's blooms can reach nearly 2', plus the purple foliage will give interest all spring and summer. All Gold Japanese Forest Grass: this plant will need afternoon shade for sure, but it keeps it's bright foliage so beautifully; it's a favorite to brighten up a shady bed. Sum and Substance Hosta: another option for chartreuse/lime foliage, these can be a sensitive to burning in the sun. For blooms: Helleborus or Christmas Rose, white or pink cultivar: these are a little smaller, but will be among the first blooming perennials to peek out in spring. Astilbe: the tufted shape of the bloom pairs really well with the mounding shape of hydrangeas. If you would like an evergreen, but are worried about size, a Slowmound Mugo Pine, Dwarf Blue Shag Eastern White Pine, or Sea Urchin Pine all live up to their dwarf plant title. None of them will get taller than 3', excluding the Blue Shag which can on occasion reach close to 4'. These will all need to have sun though, so won't be suitable for the shadier side of the porch. I hope these recommendations help a bit!

I just bought 2 large size - 3 gallons - for $23. not bad, I think.