The quantity and quality of bloom are unsurpassed. It is easily satisfied in sun or light shade in any good soil. Unfortunately, there have been too many varieties introduced that are very similar to one another. It is really a good idea to see varieties growing in a garden or at a nursery before you buy. Choose varieties from different groups within the genus - it is probably not worth growing more than two or three forms of Geranium oxonianum, for example especially if your space is limited.
Most Geraniums are easy to grow, and the majority are reasonably hardy.
They have no special needs, and require little care, although some varieties benefit from being cut back to the ground after their first flush of flower to encourage bushy growth and a second season of bloom. A few can also be propagated from cuttings taken in late summer.