Some important gardener, can't remember who, once said Rozanne was "boring" since it flowered on and on and on etc. I love it, but it does need a goodly space. I also have to support mine since they can flop over others, or the lawn edge.
The reason this particular Gerannium has such a long flowering season, so I was once told, is because a grower managed to cross an early flowerer with a later flowerer and it has kept both characteristics.
Anyway I wouldn't be without it. Haven't tried it in a basket but might be good as it would probably trail over the edges whilst keeping some bulk above it.