Heehee, it's not underused by me, I live on it! (my boyfriend and I bought a 103 foot, 75 year old Dutch barge that used to be a hotel last year and we're living on it right by Tower Bridge).
All the boats that go past are like our neighbours - some great (like the little Hollywood, or Edwardian, or Bateau or even the "big boned" City Cruisers), but others are naff and noisy (neon wonderland Erasmus, or the Dixie Queen and its tacky horn) but one company in particular are downright evil and very very dangerous drivers (that'd be Thames Clippers, who disregard slow down areas on the charts, and whose wakes have seriously injured one woman and have caused thousands of pounds worth of damage on just our mooring alone, despite huge protests by river dwellers all up and down the Thames and even action from the PLA). It was nice seeing all the big fireworks on New Years Eve and watching all the party boats do donuts by Tower Bridge at midnight.
If I had to pick one commercial cruise to go on, I think it'd be a Bateau dinner cruise. The boat is long and low with huge windows the whole way and they go slowly enough that you'd see everything, and it just looks really lovely inside...