Thank you for an informative trip report,
RTWSTARALLIANCE
I came to Sendai last year whilst my spouse was busy in Tokyo, I was able to make use of a JR travel offer which is repeated this year:
http://www.flyertalk.com/forum/japan...ll-2009-a.html
The pass is good for travel between 1st September to 31 December.
It costs 10,000 yen for 3 days of travel (dates do not have to be consecutive). This makes it a potentially bigger bargain than the JR pass with Sendai being only 3,333yen away from Tokyo.
Only to add, if visiting the Zuihoden Mausoleum and you wish to learn more about Masamune Date but, like me, you don't read Japanese, take some time to listen to the audio commentary options from the box inside the tatami mat seating enclosure that faces the Mausoleum next to the museum. The museum itself has little in English, so the bulk of the information is from the audio commentary.