What species of Agastache? The western ones like A. rupestris like it dry, but the blue ones generally like average soil moisture.

Agastache foeniculum. (Foeniculi foenicula!) Blue Lavender one called 'Lavender Hyssop' by some obscurely creative person.

I don't grow these, but what I have heard from other gardeners includes that the pollinators really like them, so you want them where you can see them, but probably not near the main doors if anyone in your household is likely to be intimidated by bees. They will seed around some, so plan on deadheading.

They like moist, well-drained soil like many other perennials, and the blue-lavender color goes well with most other colors, to my mind. So put it with anything else that likes those growing conditions, but not anything delicate that might be overwhelmed by its size or seedlings.

I am fairly sure that there are folks on the perennial forum that grow this, so if you don't get other input here, you could ask there.

I've got a couple that I grew from seed two years ago, planted at the base of some Clematis and Lonicera, next to Echinacea, in nearly full sun. That seems to work pretty well, since the bases leaf out pretty broadly, and there's not a lot of space for anything delicate next to them. They're big, vigorous plants. NHBabs is right about pollinators. Mine had spires of blooms for months last year, and bees and butterflies adored them.

The dried leaves and flowers make a tasty tea, too.

I grew some from seed last year in a container, and yes, they self seeded around the area a little bit, and yes the leaves make a nice tea, and now it's much too big for its container. Being blue/purple and kind of sedate looking, I guess they'd go well with white or light pink things.

I'm in north central CT and have multiple Agastache foeniculum/anise hyssop plants growing in my many garden beds. While they tend to thrive in full sun & sandy soil, that doesn't mean they don't pop up in my part-sun perennial beds as well. The pollinators love them. My neighbor is a bee keeper and his honey bees are on the plants non-stop each year. All of mine were grown from seed, including the original plant which I grew the first year I experimented* with winter sowing.

* 533 gallon milk jugs' worth

I'm trying to create a pollinator/butterfly bed this year. They'll be perfect there!