Thanks everyone for participating in this poll. It is interesting to see what works for others. I have been using the zoo med heat mat for awhile but when you try to regulate 2 heat mats through one thermostat it doesn't provide stable heat for both.
I have switched now to heat tape using 1 strip for my 2 bp's and another heat strip for my other 2 snakes. This way each strip (being one heat source) has it's own thermostat to produce more accurate temps. Now I just need to tweak the thermostat temps up or down to where the right amount of heat is produced in my tubs...