Fred,
The name of the pub in Garrison's Landing is Guinans. It is in the rear of the little country store on the river side of the tracks just adjacent to the southbound platform. The family that runs it has been there since the 1950's, very friendly place and a super spot to watch trains and traffic on the Hudson while you sit next to the fireplace enjoying a cold beer! The local crowd in there (which I am a newcomer to) are a wealth of information on the history of the Landing.
I also found another great spot to photograph trains in this area while I was out jogging last weekend. If you travel by car, it is on route 9D about 3 miles south of the route 403 and route 9D intersection. On the right side of 9D (the river side) Look for a sign that says "Outward Bound". Pull into that driveway and park in the lot. You will have to walk down a winding gravel road for about 1/2 mile. You will come upon a stone bridge over the Hudson Line tracks. I believe it is the bridge that appeared in the begining of the movie "Hello Dolly". The spectacular scenery you will encounter will make the walk worth your while!