PS My daffodils always seem to die out too, and I can't figure out why!
Daffs are very hardy and low-maintenance, but there are a few things they require.
Give them as much sun as possible. Once they finish blooming, they need to be allowed to die back naturally. Don't cut or braid them in an effort to make the bed look neater.
They need to be placed in a well-draining area. Also, don't plant annuals over them that require supplemental watering, because that could encourage the bulbs to rot.
Mulch them well, but not so deep that they can't grow up and out of the mulch. For those in very cold locations, you might have to dig them up.
A light top-dressing of organic fertilizer will help. There are bulb-specific types out there that work well, as does a light application of bone meal or even blood meal. An application of manure works too. I apply a very light application twice/year and rotate fertilizer sources and have had great success.
Make sure you are choosing varieties that are better suited to your geographical area. Also, there are varieties that are better suited for naturalizing then others.
You might want to check out this company for more on daff care (daffodildepot.com). I like their product and have been very pleased with them. Hope this helps!