Bearded iris is so prone to iris borer you should check it out often. I also find they do not perform well unless it is sunny dry area. Foxglove is annual/ biennial variety and reseeding can be problematic if you mulch heavily. Delphiniums are iffy to begin with and do well only in specific/ just right / places which most of us have hard time finding.
Generally plants that bloom first year will need frequent division, plants that take long to establish may not ever need any dividing.
My garden is based on plants that do not need frequent division or reseeds or aggressive enough to survive in the the world. Plants that do not divide- geraniums, hosta, cimicfugas, columbines, pulmonarias, epimediums, aconitums, heuchera etc
Plants that reseeds are campanulas which I love and have many varieites, corydalis, geranium species, primulas, columbines. Plants that agressive enough are lysimachias, euphorbias, anemones when established.
This leads me to the woodland type very informal garden where plants grow by their own design, planted very tightly and need some help but not much of it. I do not want to grow plants that need lots TLC to do well.

Can't believe there are no Echinaceas on that sun list or Rudbeckias. They are must haves along with Gaillardias.

Thanks for the observations about the plants I am complaining about. I will have to read up on Iris Borer and give a closer inspection. I thought my Iris were in a sunny, fairly dry area. I do have other plants that are encroaching on them and I seem to remember reading they don't appreciate that. I've also read an article reporting that Iris collectors actually grow them in their own separate bed because of that. Something I was hoping would not be necessary as I don't have anywhere to give them their own bed. I don't suppose they would grow well in containers?

Really too bad about the Delphiniums. They are so gorgeous.

I've had geraniums for at least 10 years and haven't noticed any reseeding.

Campanulas, huh? I do like them. Pretty sure I've had some at some point. I love the white/purple clips. Do you have to stake the tall varieties? Do you ever get groundhogs in your garden? I hear they are very fond of them. Since I vegetable garden, I try not to attract them.

I guess I haven't really tried many reseeders, except the columbines. I am very happy with the amount they reseed. Just enough and not too much. I have almost tried the corydalis, but worry a bit about too much reseeding. I have the pulmonarias and cimicifugas, some hosta, lots of epimediums and heucheras. I haven't tried Aconitums yet.

Thanks ...

Echinaceamaniac...I am not surprised you can't believe it. [g] I can't believe it either. I have often heard and read of how easy and dependable echinaceas are and have tried growing them for at least 10 years. I've tried them in the only two areas that I have enough sun for them. One area having full sun from morning to sundown. They just have not performed for me and I have no idea why. I had white swan for five years in one location and did not have to divide it. I've bought the gorgeous Harvest Moon and another of the new varieties and it never came back. I still have some purples and added more last year in a renewed attempt to establish a good stand of them. I do see they have come back this year, so I am keeping my fingers crossed. I love coneflowers and I don't know why I don't have a ton.

Gallardias, with red and yellow just don't fit my color schemes. I did plant 'Burgundy' last year and hope that works out. I tried one the year before and it turned out to be a Red and Yellow but I let it go for the season and even in part sun it bloomed it's head off all summer right up to frost.

Rudbeckias...I ripped out when they completely overran a full sun bed they were planted in. I think it was the variety 'Goldstrum'. I have had success with the variety 'Indian Summer' It has been well behaved in my garden and reseeds gently. I still have a few of them. They were a mainstay for me for about 7 years so I needed a change.

Baptisias and peonies are long lived and never need division--the former will self seed it the seed pods are left on them. Also long lived, pest free and handsome are pardancandas, most yarrows, many salvias. Many geraniums are long lived.

Another long lived plant that does not need divided is Dictamnus, commonly known as gas plant. Getting it going takes a little time, but once established it is a winner in the easy care and longevity department. Good looker all season like healthy peonies are.

I would add hostas and daylilies to the list of long-lived, little-attention-required performers :-) Another perennial that I love that seems hugely underused is bowman's root, Gillenia trifoliata. It just keeps getting better each year. If suited to your climate, euphorbias also. And if you like iris, try Siberian or some of the native species iris rather than the beardeds. They don't mind close neighbors, don't require as frequent division as do the beardeds and will tolerate varying degrees of shade as well.

I forgot to mention Baptisia. I have a nice one that has performed perfectly every year for probably 10 years!! It is so easy care, that I forgot I had one...lol. I put a hoop around mine.

Yes, I do love Peonies. At least I thought I did. But I added two to a sun bed two years ago and last year, they opened just as we got a heat wave and in four days the petals were all on the ground. Without a heat wave, what do you get a week? One developed some kind of foilage disease and died.

I have some Salvias, but with clay soil, I think they prefer better drainage. Mine look ok but not great. Yarrows are lovely and I like them, but I've left them out because I thought they travel too fast, true?

My geraniums are very easy care, have had them for years, never have a foliage problem or insect problem, knock on wood. [g] Fairly long bloom. I would like to add more varieties.

I have been interested in Dictamnus. I never see them at the nursery. The Gillenia I've never heard of. Reminds me of a Gaura or a Sweet Autumn Clematis when it is in bloom to some degree. Very nice.

I have a Siberian Iris but I think I must have it in too much shade because it doesn't bloom. I will have to move it. I am just starting to collect Hostas. I really enjoy them.

Daylilies....I am not a big fan. It's the foliage mostly. I like them when the foliage is thin and their footprint is small. But I also love the larger blossoms that come with the heavier foliage. I have been looking for a long blooming, tall, grape colored one that I like for a long time and haven't found one yet.

I love lilles and would grow tons of them if it weren't for the LLBeetle! Grrr! It's just too much trouble. I have Lily envy of all of you in areas that don't have that problem. :-)

I don't have a problem populating my shady beds. There are so many great native plants that I love. I think it is my part sun/sun beds that give me the most trouble. Sooner or later, I'm sure I will stumble upon the perfect plants for those beds. Every year, I try more.

Thanks for all the ideas!