These are some of the most comfortable Crocs out there, if no the most.  I used these up in Massachusetts when visiting my family during the holidays and they kept my feet warm outside in frigid northeast temperatures.

They were so popular among my family memebers that 2 of my brothers and both my parents picked up a pair of their own.  They are a little bit heavier than normal crocs because of the soft lining, thicker sole, and the lack of ventilation.  That being said, these will not be suitable for summer or warmer days.  They fit on your foot exceptionally well and will not slip off if sized correctly.  I am I true size 10.5 and an 11 fits me perfectly.  I think the lining makes the fit a little more snug.  So it might be a good idea to get this shoe in a little bit of a larger size.

As far as the slipper idea goes, i think these are the best slippers on the market.  The fancy memory foam and sheepskin slippers tend to wear out too quickly and become uncomfortable when they do.  Crocs just last for a long time through pretty rough use and abuse.  for the money, these are a great slipper option.  I highly recommend these shoes for either an all-round winter croc or slipper.