Actually, I can really see that Persicaria working - the picture is lovely! Might pop that in to my own garden. Beautiful links to planting ideas, Pannacotta - I shall really enjoy looking at them.
I think that verbena bonariensis, lovely as it is (yes, I've got it in my garden, and it's smashing), is starting to look a bit overdone, and might come across as a bit trendy in that setting? i.e. combination of three trendy plants together, plus meadow garden = bit naff? I read a very funny piece by Robin Lane-Fox in the FT once about his visit to a trendy garden, and it has influenced my choices since - I suppose that it was the way that he talked about that garden having no real response to either the setting it was in or the character of the people who lived there, so that it gave the impression of having been cut and pasted onto the . It's like Pope says:
Consult the genius of the place in all;
That tells the waters or to rise, or fall;
Or helps th' ambitious hill the heav'ns to scale,
Or scoops in circling theatres the vale;
Calls in the country, catches opening glades,
Joins willing woods, and varies shades from shades,
Now breaks, or now directs, th' intending lines;
Paints as you plant, and, as you work, designs.
(love the idea of a spirit of the garden helping you work!)