Thanks for a really good idea. I regularly suggest to my students that they should make lists of 'favourites', 10 best landscaping, ground cover, scented, etc. plants; or just plain 10 favourites. I loved your reference to 'tired' cottages in Britain. I have come across a few tired gardens in my time.
Here, when we talk about perennial sweetpea, we mean L. latifolius, which makes an untidy (or informal) climber to 2m. and has several lovely forms ('White Pearl' in slight shade is fantastic). L. vernus is the 'Spring Vetch' and grows to to 30 cms. or so in purple or pink/white. Sweet Peas are easy peasy here so it's nice to know that we have some advantages!