Are those LM335CZ or whatever the number is? Small temperature sensors based on temperature coeffecient, but redesigned to exploit that, and calibrated to 10mV per degree C? Anyway, I like them. But it's been too long since I used one, I even forgot the exact number.
If you need fast reaction time and very consistent swappable sensors for pre-calibrated sicruits, PT100 is nice. Bare elements about 15 quid, likely a lot less in quantity. They can stand the condensation that build up on coolers better than most stuff, but they're originally intended for heat. I like them for fast response and very low thermal mass, and very efficient thermal coupling.
Once you have bored the guests, don't forget to insert little thermistors into the holes.