I agree with that suggestion.

The Imperial is practically on top of Hibiya subway station (direct line to Akihabara), and it's only a couple of blocks from the Yurakucho JR Station on the Yamanote Line. It also fronts on Hibiya Park and the Imperial Palace. You can't visit or even see the actual palace from the publicly accessible walks, but the grounds are pleasant, and the small museum shows a rotating collection of works from the imperial family's private collection.

I'd take the Yamanote, because a large number of people will get off at Tokyo Station (the next one after Yurakucho) and because after you leave Tokyo, Akihabara is the second stop. The sequence is Yurakucho, Tokyo, Kanda, Akihabara.

If you take the subway, it's Hibiya, Ginza, Higashi-Ginza,Tsukiji, Hatchobori, Kayabacho, Ningyocho, Kodenmacho, Akihabara.

For your leisure hours, I'd suggest buying a Tokyo city guidebook--there are several on the market--and Kodansha's Tokyo City Atlas, which is what I consulted in order to refresh my memory on the location of the Imperial and the sequence of subway and train stops.