(love your name, BTW - meaningful on many levels!)
Oils and fats is a good subject for further reading - search it out on the net; it is amazing how many important body structures need 'good' fats.
Virgin, cold-pressed olive oil is great on some salads, a bit strong for others. Great to even have a sip early in the morning (good for the gall bladder and liver). When sauteeing or frying, use the medium olive oil and don't let it get too hot and add some butter as the bell whether (butter burns quickly).
There are many wonderful oils around; grape, sesame are just some - I recently brought back a truffle-flavoured olive oil from down Margaret River way.
Most commercially available oils have some TRANS fats (due to hydrogenation caused by heating to extract all the oil out of the nut).
The commercial peanut oil also has a small amount of TRANS fats as above, but the high flash-point ~ 270 Celsius makes it perfect for frying; Asians use it extensively.
Apparently the healthiest oil of all is cold-pressed coconut oil - a bit hard to get. Formerly coconut fat/oil used to be used in many commercial bakery products, nowadays replaced by cheaper margarines and cheaper oils.
