These 32oz 1 litre Tatonka 18/8 Stainless Steel Bottles look quite good and appear to be very lightweight for Stainless Steel so must be very thin walled at 210 grams (7.4oz). This compares to the Sigg Aluminium at 145 grams (5.1oz) and the Guyot Designs Wide-mouth 32oz Stainless Steel at 348 grams (12.1oz)

http://www.amazon.co.uk/Tatonka-Stainless-Steel-Bottle-1000/dp/B000G4XI3G



Insulating covers are available and will help prevent the the bottle getting the inevitable dents. Although looking at the bottle shape and size the SIGG Neoprene 1 litre covers would probably fit as well



http://www.tamarackgroup.co.uk/acatalog/Cookware__eating_and_Drinking.html