I have successfully used the Microchip MPC9701. Since it has an analog output, you can run the signal 50' or more. Just use a low-pass filter (2K in series, .1uF to GND) with the A/D input and average 16 samples with a 1mSec delay between samples (so that you average out over one complete cycle of 60Hz). The output is linear with temperature (unlike thermistors), and doesn't need calibration. Cheap, too.