“Westminster Abbey tour 9:30, Thames River boat to Kew at 11am, lunch? Kew few hours, explore Richmond. Add Hampton court?”
I am exhausted just thinking about this day. (smile) Definitely do NOT add Hampton Court. You need at least half a day to get there, see it properly, and get back into town.
“Should I switch these days to allow us to visit Borough market when it is open? How nuts is this place with crowds?”
If you are at all a foodie, I would say “yes, visit when it is open.” There is no “visit” when it is closed, frankly. You will see the space, but miss the experience. (Although if you do visit when it’s closed, you could pop into Southwark Cathedral, which is lovely, and often overlooked. You could budget 30 minutes for that, to get a flavor.)
As for how nuts it is? IT IS NUTS!!! If you do elect to go, get there right when it opens, before the crowds become oppressive. It is also an ideal place to have lunch, so, two birds. I recommend Padella for excellent pasta: https://www.padella.co/ - or for superb oysters at a great price, try Richard Haward’s Oysters: https://richardhawardsoysters.shop/
“Tour both Westminster and St. Pauls? They both look beautiful. Worth it?”
Both are way beyond “worth it.” If you have to choose just one, others are saying to visit Westminster Abbey, and I concur. But they are both magnificent, each in its own way.
“Our other days consist of exploring Kensington, Chelsea, Regents Park, Hampstead, Marylebone, Mayfair
Things we may forgo, Tour of Buckingham palace, Tower of London, and Portobello market. (I love antiques but not trinkets, Is this wise or am I missing out?)”
Portobello Market has real antiques, but also trinkets. It can be packed. If you love antiques and are in Kensington or Chelsea, you can just duck into any small local antique shop you pass (and there are many) to scratch that itch.
Hampstead is gorgeous but a bit of a jaunt from central “tourist” London. With only 4.5 days, you might want to give it a miss, in the interests of time. Remember what Rick always says: “Assume you will be back.” :-)
“Is the river cruise to the Kew lovely? vs maybe a boat cruise in Little Venice? or both?”
Remember to say “Kew Gardens” rather than “the Kew.” :-)
Little Venice is adorable, but more neighborhood-y and less of a “major” site. I love it there, but might be tempted to leave it out of a short visit.
Agree that you can leave out a tour of Buckingham Palace. Concur with those who have suggested that The Tower of London might move closer to the top of your list. It is MAGNIFICENT. It is OLD. It is AMAZING. Enough said.
Hope you have a blast!