For those of us that suffer from these miseries...
I have recently come across treatments that have really worked for me, maybe they will work for you.
Plantar fasclitis. Try this simple excercise. Sit so that your right ankle is crossed over your left knee. Now grab your toes on your right foot and pull them back and hold for 5-10 seconds. Repeat several times before switching legs. Try doing this 2 - 3 times a day...especially in the morning. This stretch has been shown to eliminate the pain in 75% of the patients of Dr. Giovanni of the U of Rochester.
For foot/leg cramps...bite your lower lip. It is a form of acupunture. It works almost instantly...well almost.
Regular yoga and stretching excercises also work to eliminate both of the above.