I've had great success with peonies in my garden, and I think the key is to give them a spot with plenty of sunlight, at least 6 hours a day, and well-draining soil that's rich in organic matter. I've found that a slightly acidic to neutral soil pH, around 6.0-7.0, works best for them. As for spacing, I plant them about 3-4 feet apart to give the roots room to grow and the plants enough air circulation to prevent disease. I've also noticed that peonies don't like to be disturbed, so choose a location where they can stay put for a while, and make sure to water them regularly, but not too much, as they can be prone to root rot.