All trains start and end at the Essex Station, located on Route 154 at Route 9 Exit 3. Christmas trains generally go to northern Chester, whether it be CMX or Parker's Point, but generally your last public viewing will be at the Ferry Road crossing (Route 148) in Chester. There are stations in Deep River and Chester in between, at Deep River is the passing track, so a train backs down from where it stops in Chester back to Deep River.
You can go to Google or Yahoo Maps and search the railroad, beginning at the intersection of Main St/Middlesex Tpke & Railroad Avenue, heading north. All crossings are at-grade except Dennison Road and Route 9, both in Essex/Centerbrook. Rattling Valley Road is kinda tight, but views from Essex St and from the town landing at the end of River St in Deep River are both possible.
Looks like departure times for the holidays, starting day after Thanksgiving, are 1pm and 2:30pm, and night departures are I think at 5:30 and 7:30, though are no longer listed since they are all sold out (for now). Info courtesy
www.essexsteamtrain.com.
Enjoy!