Take hotel bus to Shinagawa Station. Bus lets you off across the street from station. If you have a lot of luggage you can walk to the corner by the little mall and cross the street without using overpass. Entrance to train is right there--outside station. Use Keikyu Line. Very quick and easy. (if you dont have luggage you could use the overpass to cross the street but that requires many steps).

Coming from Haneda TO hotel I used the Narita Express to Shinagawa Station. Not sure if I was allowed to as I just paid regular rate with my Suica pass (there were no English signs that it was a special train with special ticketing) but I never had to show a special ticket and had no problems. It was nonstop Haneda to Shinagawa in about 15 minutes. Beautiful.