A friend of mine whom I have been hiking a lot with lately made me aware of a really great thermos. It's a stainless steel model from Thermos. I had memories of thermos from my childhood - they worked ok, but were only good for keeping something hot or cold for a few hours, plus they had a glass interior which could be easily broken if you dropped the thermos. Either my memory was flawed or they have improved the technology substantially in the past 30 years. This new thermos is all stainless steal and according to the marketing material, it will keep hot water hot for 24 hours!!
I admit I was skeptical until I experienced it first-hand. On a hike up a mountain in 30 degree weather, I was able to have piping hot hot chocolate 6 hours after the water had been put in the thermos. It was so hot I had to leave my cup in the snow for a few minutes to cool it off enough so I could drink it. And now, about 15 hours after the water was put in the thermos and the thermos spent most of the day in 30 degree weather on a mountain, I just made myself another cup of hot chocolate and it is still extremely hot - hot enough that I have to sip it to drink it comfortably. Granted, I haven't tested it for a full 24 hours, but I'm very impressed with what I've seen so far. If you are looking for a good thermos, this is the one to get!