For non-gear sandals, I really love Jambu. I have two pairs that I can wear all day with no problems. My favorite are the espys because it gets so hot here and they are like barely wearing shoes.
http://www.amazon.com/Jambu-Wo.....038;sr=8-1
I also have these
http://www.amazon.com/Jambu-Wo.....38;sr=8-15
I also have another older model that I can't find any more. In my experience anything Jambu with a heel under 3 inches is good.
For gear type shoes, I love Keens. I have H2s and an older model that is more strappy where less of your foot is covered. I couldn't find them online, but most of the keens I have tried have been great.
For me, for 12hr sandals it's important that I can easily clean the insides. With it over 100 degrees here most of the summer, there's going to be foot sweat. I can't do anything with suede liners or anything else that would get yucky.