Depends on the car and the plugs used. The plat or iridium plugs normally are somewhere in the 75k to 100k mile mark. Copper plugs I believe are closer to 5-10k miles mark.

For a tune up, I would...
Replace plugs and wires
replace air and fuel filters
Change transmission fluid
check brakes
flush radiator, change to green, replace thermostat.

Depends on whats been done to the car already too.

Jesse