Best Thames return river cruise

[BrassCandlestick]

I'm taking friends from abroad for a trip to London and I'm looking for the best value river cruise. We don't have enough money to get off to see the Cutty Sark etc so I'm just looking for the best (and most reasonable) return trip.

Get a day pass and hop on and off on the UBER Thames Clipper boat and you can find various commentaries/videos on line.
You can ride all day hopping on and off
I live in Westminster and usually take the dog down to Greenwich- do the park- back to Bankside/Tate Modern/Globe/wibblywobbly to St Pauls and then get back on and down to Battersea. But many options available

https://www.thamesclippers.com/explore-london/river-guide

Uber.

I should have said I don't want to use the Uber service

Also don't need to hop on and off - we haven't got the money to enter more attractions. I'd just like a simple cruise up and down guided by a swarthy sea captain!