I plan on planting only perennials in this bed, if I find enough that I like.

There are also perennial leeks of a couple of types, Down south there are also quite a few local varieties of elephant garlic. In your area many multiplier onions are quite hardy - that do not need to be dug every year. Like elephant garlic, there are quite a few local varieties, many family heirlooms.

And there are a number of different types of walking onions.

Virtually all ornamental alliums are also edible, some more than others of course.

2 caveats:

first nearly all perennial alliums have a dormancy period at one time or another during the season; so there will automatically be open spots in your planting, when depends on the type of allium

and second chives and garlic chives are very pretty in bloom and both are quite edible, but they also produce prodigious amounts of viable seed making them extremely invasive if the flowers are not removed before the seed ripens.

Another option is Welsh/bunching onions (Allium fistulosum )lots of varieties to choose from. Evergreen, Crimson Forest, He Shi Ko , Deep Purple etc.

I have a 3'x3' bed of overwintered Evergreen White bunching onions that I still have not gotten around to dividing this spring. They are growing like crazy already but I don't really have anywhere to plant them. Hoping to pawn some off on my brother from Minnesota when he visits this weekend.

I would get some Heritage Sweet perennial onions. They are bright white unlike the walking onion yellowish type. Not as strong/hot tasting as designated by the "Sweet" in the name. The vendor below is where I ordered mine.

http://www.egyptianonions.com/Pages/catalog.html