Chinese snowball viburnum (Viburnum macrocephalum) produces large, softball size, hydrangea-like blooms both in the spring and fall. However, I must admit that mine is much more of a show off in the spring than in the fall. The blooms are so profuse in early May I wonder how the plant can support them.
It is a big shrub, well suited for large gardens where it can be enjoyed from a distance. Gardeners will limited space can train Chinese snowball viburnum into small multi-trunk tree so you can still utilize the area under it for planting perennials and annuals.