Why would I use a thermistor instead of a LM35/36?
Thermistors are cheaper and smaller which is useful for applications where many points have to be sensed and little room is available.  They can cover a wider temperature range than the LM35.  They only have 2 leads and require less power per sensor since many sensors can share a readout circuit.  They can also provide higher accuracy if needed.  For example there are oceanographic thermistors deigned just for measuring the temperature of seawater that are accurate to less than 0.1 C degree over the -5C to 35C range. They are useful in circuits where a temperature variable resistor is needed instead of a voltage proportional to temperature.