I replied to your message, but I'll give a short reply here too. We arrived at Tokyo Station via Shinkansen from Osaka. Whether you are coming from somewhere else in Japan or the Narita airport, you'll go through Tokyo Station. As a major hub for the Shinkansens and the airport trains, Tokyo Station is very tourist friendly!!! Transferring to the Keiyo line from the central station is pretty simple and obvious - you'd have to try to get lost. Everything is clearly labeled in English and color coded (you want the RED train line, in this case.) It's a 10-15 minute walk - there are moving sidewalks, escalators, and elevators so it's not bad. The Keiyo line serves a ton of Disney tourists so there are less business commuters and you'll see a lot of other people with luggage (and Duffy Bears the size of 5 year olds...) The hotel I recommended is just a few train stops away at the Shiomi station stop (express trains will skip this stop so just make sure you take a local train - again, clearly labeled!) It's a very small station - easy to navigate, impossible to get lost, luggage is no big deal. The hotel is right across the street (or you could take a taxi, I guess - there are always several waiting. It really is just across the street, though.) We've stayed at several hotels in Japan and getting to this one was relatively simple. We love the trains and get JR Rail Passes so that's the only transport method we've researched/used. There are definitely other options!
Hope this helps!