My geraniums mostly survive in the conservatory and I wont cut mine back until absolutely neccessary. Make the most of the colour while you can. I had some in bloom all last winter and in the spring just cut them back a bit and renewed the soil.
If there are any really good ones, you could put them on the kitchen window sill and they will bloom all winter.
Whatever you decide to do with them, take some cuttings just in case. Put them in dryish seed/cutting compost and leave on kitchen windowsill.