I keep thinking I want to do that ride in one day (MI C2C - Coast to Coast in June), then I think that would just be painful. A week sounds like more fun.
I did the shoreline west - that was a nice ride (with a day off in the middle if you wish). My wife and I would just take our time, enjoy the day, and chuckle at the lycra guys who sprinted to the end every morning (yeah, normally I might do that). The most important part of getting in shape for that is to make sure your derriere is comfortable with that much time in the saddle.
We enjoyed doing the ride on fatter tires. (40mm for her, 55mm for me). I was surprised that almost everyone seemed to be on 20 something road tires. Given the low rolling resistance of larger tires, I think something between 35 and 40mm would be the sweet spot for a tour like that.