I love Roxanne too..it flowers forever. Apparently some clever hybridiser crossed one geranium that flowered early with another that flowered late and, hey presto. It is one of the bigger geraniums and needs a bit more space than most so I have to be a bit careful where it goes as it can flop over the plants nearby
Two other hardy geraniums of huge merit...psilostenum which has the most magical black-eyed cerise flowers that stand out in the crowd of often dull/pale pinks and mauves of the pack. Second Ann Folkard..a great favourite of Christopher LLoyd who grew it because it wanders around and climbs up throuh the plants nearby enhancing them with its yellow/green foliage and cerise flowers, again with an "eye". For example try it alongside lavendar.