Having been on the Antarctica trip and now looking back at the pictures that were the most successful .... the lenses and accessories I found most helpful and successful were .... peripheral battery (such as the Digital Camera battery Michael has described ... keep the battery under your coat and use the extension cord that comes with the camera, others said I wouldn't need it ...wrong), 35 mm 1.4 with pano head, 24-70mm zoom, 80-200mmm zoom and 400 DO with a 1.4 TC in my pocket at all times.... and polarizing filters for all lenses. One other lens that in hindsight got some great "ohhhh .. how did you do that shots" was the Canon 15mm. Given your list you should be in great shape except the 2X TC may be a bit long (and dark) for hand holding, auto focus and if many overcast days such as we had. My only suggestion then is to make sure you have your power requirements covered (remember in the summer months its a longgggg day so even if the cold is not a problem, the hours of shooting will challenge your batteries) and consider taking at least a monopod.