I've had a number of stays at Sheraton Yokohama when rates in Tokyo were outrageous. The Sheraton is right next to Yokohama station, though, which has trains that get you to various parts of Tokyo in 20-30 minutes. The ICs are less favorably located, so you'd likely have to budget 45 minutes to an hour. Note that Tokyo is a HUGE city, and if you stay in one area of Tokyo, you'll have significant travel time to another (for instance, getting from Shibuya to Ginza can take half an hour). If you were on business in a specific part of Tokyo, the daily commute from Yokohama would likely be a drag, but as a tourist visiting different parts of town, you'd spend a fair bit of time positioning every day anyway. So if the savings are right and you don't mind some hassle, Yokohama can be a decent base. It's also a fun city to explore, and it's convenient for some non-Tokyo daytrips like Kamakura. Note that trains are packed during rush-hour, so it makes sense to pay a few hundred yen for Green Car, where you can sit.