As a 2010, 2011, 2012 & 2013 Tokyo Marathoner (but not 2014 - having a year off!), I can guarantee you that you'll love this race. Great crowds, fantastic organisation, and the biggest, craziest expo going! If you have any questions about the race, the city, getting to and from the start/finish/Expo, let me know and I'll be happy to help.
I think my post marathon plan is to "retreat" to the hotel, get a massive pizza and a few beers from the All Star Sports resort food court, dangle my legs in a pool and partake in a few tinnies and a few slices of pepperoni!
All with 6 medals hanging around my neck (2 of which say "inaugural"!).
I especially like the "inaugural" engraving on the Dopey medal. Makes it just that little bit more special compared to what they'll give out in future years. And if we receive the Dopey, Goofy and Marathon medals after the last race, then we'll all get that taste of what its like to be Chris Hoy draping numerous pieces of bling around his neck during the Olympics.
My 1st and 2nd marathons (Tokyo 2010 & London 2010) were also 7 weeks apart, and while the last 6 miles of London were physically and mentally quite tough, its certainly not impossible. Different people have different methods, but heres mine:
Ive always found that the midweek runs can be mixed up to suit your own schedule, so if you do 4 miles with the club one day, do the 6-7 another day in the week when its more convenient, but the most important thing is the long runs at the weekend. Stick to a rigid schedule for those and dont deviate! If you miss a midweek run now and again, its really not the end of the world, but miss one of the long runs and you'll be making it very hard for yourself.
After the first race, give yourself enough time and rest to fully recover (I think I did absolutely nothing for 2 weeks!), and then try to keep yourself ticking over until the 2nd race. If you do too much in that 7 week period, you'll pay for it in the race. Its a balancing act, but listen to your body. And good luck!