I save my own seeds as well (some at least) and it is a good strategy . I only grow dwarf beans these days, I tried runner beans once and none of my lot would eat 'em .
Have you tried sacerlet runner beans? they are perennials and have nice red flowers.
Scarlet runner beans are also called seven year beans or multiflora beans are a species themselves - Phaseolis coccineus.
The beans are large and are coloured half pink half black.
I have only grown beans as an annual becaue the frost gets 'em, but the scarlet runners die back and then sprout again the next spring from the same root.
I too have started off a load of beans (cheers), I quite understand why allotments up and down the country have beans on them I could not belive how much came from my one plant last year. (the first year I grew beans) I think that I too will be growing soe every year. They are good plants in a crop rotation system too because of the nitrogen that they absorb.