S.C.
I am a sitter myself and also a mother. I think the best thing you can do is to let each sitter have some time with your son. You'll know if they click or not. You can hire the most experienced sitter, but if they don't click with your son it won't matter. Also ask what kind of activities he/she will do with your son. Will it be just unorganized play or more structured. Also, be very clear on you wants and needs. Make sure the sitter knows exactly what your expectations are going into the job. Good Luck!!!