I think you would be better off with natural stone if you are trying to keep with the period of the house. Buff colored SRW walls maintain no true authenticity and not matter what you do, will never look like they've always been there. Go with the clay paver or brick and possibly some flagstone. Stacked stone will not clash with either.
I say keep the hardscape materials more classic and do whatever you want with the plantings. Giving them 4 season interest will mean more to the HO than having 4 months of a landscape that may or may not be authentic to the time period. Holly would be a good choice. Either traditional holly varieties, or newer ones like Red Beauty, Dragon Lady, Winterberry or Inkberry Shamrock.
Whatever you do....please don't put those antique hitching posts atop a SRW wall. That would be an injustice.