Now stop me if you've heard this before (too late!) but there's the ideal lens for my kit sitting lonely on a virtual shelf: the Tamron 17-35mm f/2.8-4. I had this on my Sony A200, my first really great lens - yes range is thin for 440g and it takes 77mm filters. On the other hand it doesn't prevent the DA40 from playing, it's fast and decently wide, and I liked its images a great deal four years ago.
And hey guess what: it's full-frame capable. That may not interest me now, but it may interest others in a year or so. If money comes at me and I cannot duck, even I might care - but it will serve well on the 18×24 sensor in the meantime.
Retro part IIAfter adding it to my cart and then deleting it, I re-added a Sigma 28-90 with 1:2 macro. The label says Quantaray but it's the Sigma 28-80 by any other name, and was another of my A200-veteran lenses . Yes it has a plastic mount, yes just f/3.5-5.6 - but also yes close-focus ability at almost 1:2, yes 8 aperture blades, and oh yes 220 grams and a low price of $35. When I don't need to go wide this lens can do most of what I do on not-really-out-for-imaging days; when I want to be serious the Limited primes will do the job best. It will be fun comparing the Promaster 100 to this at 90mm, as both can do about 1:2 closeups.
And hey guess what II: it's also full-frame capable.