Two days in Tokyo. Advice please!

Hi, I am an elderly, but mobile person who will be returning to Tokyo
for two full days in September and would appreciate comments and advice
on my proposed sightseeing. My hotel is in the Shinjuku district.
Tuesday: Marunouchi line to Otemachi and a visit to the Imperial Palace
gardens. Then from Otemachi by Hanzumon line to Kiyosumi-Shirakawa and
change to Toei-Odeo line to Ryokoku and after a visit to the Odeo
museum, return to Shinjuku on the same line.
Wednesday: From Shinjuku, Toeei-Odeo line to Shiodome and change to
Yurikamome line to Fune-No-Kagakuka and visits to the Museum of Maritime
Sciences and the National Museum of Emerging Science. Now here is where
I am unsure! Can I go from the museum district on Odaiba by boat to
Asakusa? If so would like to do this and then return to Shinjuku on the
Ginza & Marunouchi lines.
Any comments, suggestions or advice will be appreciated. As you cansee,
I like museums!
Thanks
Spencer