I've done temperature sensing using many different technologies, and all of them have - issues. Overall I like precision thermistors the best because their performance is very accurate, repeatable, and interchangeable. That is, I can plug in a new sensor and not have to recalibrate anything. The bad news is that they are weirdly non-linear, so to get a digital readout it takes a small microcontroller like a PIC with a lookup table in firmware. Not hard, but not a beginner-level project.
Solid state temp sensors can be very linear, but both the absolute accuracy and gain function vary from part to part more than a few degrees. So as long as you don't care of 70 really means 65 to 75, they're fine. Adding a gain and offset trim circuit reduces this error greatly, but to calibrate it you need two known temperature baths pretty far apart, as in post #3 above.
ak