Best place to monitor temp.?

I was wondering where is the best place to monitor the temp. inside my ECB. I have done the mods and currently just stick a thermocouple down through one of the holes I drilled for my top vent. I stick it down in approx. 4-5 inches so it ends up just above whatever I am smoking. For example, yesterday I did an 8 lb. butt and the thermocouple probe was hanging just aboive it. I'm thinking of putting in a thermowell that will allow me to slide my thermocouple in and out more easily. This will be a permament spot so I need some opinions on where that spot should be. My original idea is to put it just above the cooking grate and in about 3 to 4 inches so it can be as close to the meat as possible without actually restricting how much meat I can put on. I'm also considering doing another one just above the lower grate so I can monitor both cooking surfaces. Will these locations give me the most accurate reading of my cooking temp.? Thanks in advance.