Hi,

I live in Tokyo. Shinagawa isn't the suburbs, but its not the noisy, clangy, bright center either. Which is probably a good thing. Shinagawa is on the JR line, which is the main line that circles the city. You won't have a problem getting anywhere from there.

500/day seems really steep to me, but it depends on the level of service and personalization, I guess. Don't worry about the car, you don't want to be driving and parking. Take the subway,and Tokyo is a great walking town. Feel free to PM me if you have specific questions. I've lived here for 6 years, so I don't really have a tourist perspective, but I can tell you if you're getting ripped off.