Hello,
Here is a website where you can find a map and discriptions to get there. In the menu you find 'how to spot' there you find the info you need for Pisa Airport.
http://digilander.libero.it/pisairport/eng/index.html" onclick="window.open(this.href);return false; . Pictures I take at Pisa ae here
http://www.sidewinderpics.fotopic.net/c658823.html" onclick="window.open(this.href);return false; all taken at spot A.
For Grosetto I've some coördinates where you can take good pics of landing aircraft. I hope it works because I don't know to put the points in this message. Here they come, 42°46'35.11"N 11° 5'4.33"O , this is at the north side of the field. For the south side, 42°44'41.17"N 11° 3'38.72"O . I take the coördinates from Google Earth.
Good luck and i hope it helpes you further.
Greetz Arthur