As a couple, Sumida River Cruise works.
A relaxed, low-effort way to see a different side of Tokyo from the water, passing under a string of bridges with Skytree behind you — the sci-fi Himiko/Hotaluna boats are a fun draw for kids. It's scenic but gentle: don't expect drama, and on a grey day it's just a pleasant transfer between Asakusa and Odaiba.