Whatever you decide on do you research. The only book I trust on savannah monitor care is
"The Savannah Monitor Lizard - The truth about Varanus exanthematicus" By Daniel Bennett and Ravi Thakoordyal. Daniel Bennett is a worlds authority on monitor lizards, and is currently involved in monitor conservation projects through out the world. Check him out at mampam.com.
I don't mean to offend anyone, but the sad truth is that most 'dog tame' savannahs are just slowly dieing. I use the savannah in my avitar for education and I trust him completly, but he still lets me know when he is in a bad mood by tail whipping and hissing.
Please read this book and pass the information on.