The best luck I had when I was trying to find the old road bed was to come at it from the east. I drove from Chama to Dulce where you can see much of the old ROW. Then at Dulce, I drove west, past the new casino and along the canyon to the Navajo water tank. Much of the ROW to the tank is now the road. At Dulce, you can still see the old station/warehouse (?) and two stock cars (For sheep).
From Navajo tank the road follows the old ROW as a dirt road until you get towards Jaunita. THis is now mainly a ghost town. There is (was) an old church and school house and a few other buildings, some still in use. You take the left fork and you an see the ROW down along the river. It is only a few more miles to Gato. Along the way there are I think three bridges still standing.
From what I understand Gato is now pretty much gone with the old Gomez Store having been moved to Pagosa. I have not heard if the old water tank is still standing, as it was leaning heavily the last time I was there about three years ago. There was also a section of track that the Utes did not allow the scrappers to have as well as a pipe car and the bridge. Also there was a beautifly preserved steam pump in the pump house for the tank. If I had a way.....don't know if that is still there, it really needs to be somewhere safe.
From Gato, follow the road to Arboles. The ROW parallels the road all the way. The road is dirt the entire way, but the car I had at the time, my trusty Ford Aspire handled it with ease. I even went in on a rainy day.... The 'new' bridge over the San Jaun is still standing as well as several others from the realignment.
At Arboles the tank and two gons on a section of track were still there as well as the station.
You can then follow along to Allison on the paved road. I forget the numbers, they are on any atlas. You lose the ROW as it loops toward La Boca, but there are a couple of trestles back there as well as the tank (If memory serves). As you come back towards Falfa and that area, you lose the ROW in all the new housing and such, but it is possible to catch pieces of it as you go.
I found a bunch of my pictures from my travels there just the other day. I do want to go back this summer.
If I made any mistakes or left something out, I am sure someone will be happy to add it in.
Happy travels!