These huge snowflake decorations are about 220mm across and were generated with my Snowflake Machine: http://www.thingiverse.com/thing:1159436.

The models are optimized for printing on an Ultimaker 2 with ABS and the standard .4mm nozzle, at .1mm layer height. They take up almost the entire built plate of the printer. If you want giant snowflakes that are already tested and ready to go, then print these.

But it's much more fun to go make your own, so go do that with the Snowflake Machine at the link above! For 200mm snowflakes, set the "Target Diameter" to 200 in the "Global Size Settings". At this size you can easily create snowflakes with 8 or more more steps!