Some Daisies are perennials;
I've had Shastas forever, & they return year after year.

Also, some annuals "return" year after year because they self-seed;
although they're smaller plants than you're talking about, Profusion Zinnias self-seed beautifully.

You might post on the regional forum for your area (Southern, New York, Far North, etc) to get responses from gardeners with experience in your climate.

You might be able to get 'daisy' bushes. Search on 'Federation daisies'. They come from Australia and can cope with hot weather quite easily.

Dahlias come in many heights and styles. Grow them as you would grow potatoes - good soil and reliable water. The big 'tree dahlia' will grow six to ten feet but it does flower quite late in the season and is often finished by frost.

However, there are others that will grow to six feet, so long as you give them a supporting stake.

You can go for a 'cool' colour range - white, pinks, sft orange, pale yellow; or warm colours - reds, oranges, strong yellows, two-colour and purple. Just not blue.

They aren't really annuals. Give them a year to make size. If your zone is 8 or below you may have to lift them each year and store them in a frost-free place.

Once they look like a clump of sweet potatoes with many sprouting stems they will flower for months until the frosts come so long as you can give them water in dry times.

In our area (zone 6) dahlias begin blooming in late May and go through until the first hard frost. They're fairly heavy feeders; we grow ours the same way we grow tomato plants. We mulch heavily with leaves in the winter so we don't have to lift all the tubers every year. You have to be sure to cut them to the ground as soon as the upper stems get frostbitten, so that the frost doesn't get down into the tuber and kill it. Typically we have to lift individual varieties about every 3-5 years & divide them.

Don't know what zone you're in, but beware; those miserable Japanese beetles seem to love our lighter-colored ones!

Daisys are perennial...
There are many varieties of daisys and as far as I can think all are perennial blooming for only about a month out of a year. If you cut them back you may get re-bloom in the fall.
Dahlias are tubers. They continue to bloom until frost, once they get started, but take a while to bloom from a tuber, unless yous tart them inside in the winter. But you have to lift the tubers before frost.
You don't say where you live...but if you are looking for big showy annuals, think of zinnias, cleome, marigolds and a tall variety of ageratum, if you can find it.
I used to plan and plant the annual beds at the Arboretum, which were 3 beds 40 by 15 and a long way from the street.
I got a lot of mileage out of tall snapdragons, salvia faranacea, tall marigolds, cleome and vining nasturtiums
You will get a much longer flowering time with annuals....but you will have to plant every year.
Linda C