i lived in Saugus for quite awhile and grew up in Revere. there really isn't much traffic free or little traffic rides there. you'll have to deal with some no matter what. a simple ride for me was to go up Essex St into Melrose. turn right on Main St and head into Wakefield. from there you could ride to the lake and loop that a few times or head up Haverhill St in Reading. make a u-turn at Harold Parker state forest and head home. riding on the North Shore and out West is your best bet for good riding with little traffic.
www.ecvcycling.org would be a good site for Northshore rides, check some of the local shops too, they sometimes have rides starting there also.