One full day in London

Start your full day at the Tower of London which opens at 9am most days. When done (after 2-3 hours), catch a #15 red bus past St Paul's to Charing Cross/Trafalgar Square. I would then suggest lunch at Cafe in the Crypt, St Martin in the Fields.
After eating, walk down Whitehall, past Horseguards and Number 10, to Parliament Square. Get a view of the Houses of Parliament from Westminster Bridge, then visit the Abbey. Walk thru St James's Park, past Buckingham Palace, then thru Green Park to Picccadilly. End your day in a Soho bar/restaurant, after some gift shopping in Fortnum & Mason.

Thank you. That sounds like a great plan.

You asked about tickets to Tower of London and Westminster Abbey. Just walk up and buy on the day of your entry. If you do as David suggested, you will be at the Tower early enough that there will be no line to get in.

Same with Westminster Abbey, just walk up, pay, go in.

You mentioned the London Pass. Yes, the way I've mentioned is much less expensive than the London Pass, which you do not need.

"read in RS book that touring the jewels might be less crowded late afternoon. True?"
Do the Tower of London first thing in the morning when they open. Go straight to the jewels. You may be the only people in there, or there may be 3 or 4 other people there. I was not all that thrilled with the jewels exhibit, so it took me about 10 minutes to do a walk in, walk through, walk out. Then come back out, do the Yeoman warder Beefeater tour. Free with your paid entry to the Tower.

Then go into the White Tower. This is very interesting. Full of displays of armor. Then walk the walls, going up the spiral staircases. Look in the small towers, such as Cradle Tower.

David has an excellent suggestion to then take the Number 15 bus traveling west to Trafalgar Square. You catch the Number 15 bus on the street above the Tower. Walk back out the entrance, turn away from the river, walk north past the hot dog/ice cream food truck and walk north up to the street. Go right to the bus stop. Wait there for the bus. It will have the number "15" in its header over the windshield of the bus. Use your Oyster card (tap it once) to get on the bus. Buses do not accept cash.

Yes, do buy an Oyster card for each person. Put ten pounds on each. It will make your day in London a lot easier. You can get a refund for the Oyster at Heathrow when you leave.

As an alternative to using the Number 15 bus, you can leave the Tower of London, go to the waterfront pier right next to the Tower, get on the river boat Thames Clipper, and ride it to the west to Westminster Bridge. You will know when to get off because you will pull up to a pier near Big Ben and Parliament buildings.

Use your Oyster card to get on the Thames Clipper riverboat. These boats are blue and white, and offer the absolute cheapest way to ride the river when you pay with a tap of your Oyster card.

If you are going to do the river boat ride instead of the Number 15 bus, you will want to eat before you leave the Tower of London. They have a very good and reasonably priced cafe inside in the southeast corner of the Tower, called the Armouries Cafe. Good salads, sandwiches, soups, pasta dishes, daily specials such as beef stew. Desserts, coffee, tea and soft drinks available.

If you do the river boat ride to Big Ben, you are then walking distance to Westminster Abbey; it's one block away.

After the Abbey, you would pick up the rest of David's suggestions, beginning with "Walk thru St James's Park, past Buckingham Palace" etc.

Do take a good map of London with you on your trip.

So you understand Oyster, it is an electronic wallet. You pay a deposit and then load it with whatever sum you want (not separate tickets). You tap at the entrance to the Tube, and then at the exit when the correct fare will be deducted. Bigger stations will have fare machines where you can check the amount remaining on your Oyster. Works for buses too.

To add to what Southam said, you tap once to get onto the bus. When you exit the bus, you do not tap it again. Just exit the bus.

With the tube, it's different, as Southam said. Tap when you get on, tap out when you leave.

Instead of lunch in Crypt, you could plan your time to have tea at Fortnum and Mason, which is walking distance from Trafalgar Square. If you eat a big breakfast or some snacks, you could skip lunch and this could be your dinner. They have a pianist and it is quiet and relaxing-best to reserve ahead. Don't be tempted to use the Thames boat for anything other than transportation from the Tower to Westminster-I thought the cruise itself was a waste of time.

Thanks, everyone. The jewels is a must as we are in the fine jewelry business and have studied the Crown Jewels for years and trained our staff about the historic diamonds. My husband and I have seen them, but our travel mates haven't. I think another question is if 4 people sharing a cab is less than 4 Oyster card rides. I do know the tube is way faster/efficient so that is a plus.

If you are interested in jewels, I might suggest finding SOME way to stop by the V&A to see their jewelry collection. They are open until 10 pm on Fridays, so that may be the best time. It it is one of my absolute favorites.

https://www.vam.ac.uk/collections/jewellery

I agree with above recommendations otherwise. Last time we went, we went to Tower of London first thing in the morning - very few people around.

I was also just getting ready to post about the V&A Jewel Collection. You must see this! Several thousand pieces from all time periods. Pieces from Tudor England, and all over the world. There is an exhibit on one floor. Just when you think you can't look at any more, there is a spiral staircase going up to another level, and there are hundreds more pieces there! Fabulous!

The V&A has a cafe which serves an excellent lunch and afternoon tea.

Hi Cathy & All,

Cathy, how wonderful it must be to know about historic diamonds!
Since you know you want to visit the Tower and Westminster Abbey, your day is pretty much planned.
There are so many choices but in the evening one thing you could consider is ice cream at Covent Garden. There is a place called Venchi which has delicious flavours and is right beside the pit where musicians perform. Covent Garden is usually pretty lively with music and other entertainment inside and out.

Having said that, I wouldn't be surprised if you just follow your nose to whatever interesting thing comes along. That's the beauty of London; you don't need a plan.

Depending on your energy levels after the flight, you may not feel like doing too much on Friday evening. But just fyi there are some places open late on Friday – the British Museum is one. Also the National Gallery and National Portrait Gallery, according to this list http://www.visitlondon.com/things-to-do/whats-on/art-and-exhibitions/late-museum-and-gallery-openings-in-london
EDITED TO ADD: V&A open Friday till 2200h. https://www.vam.ac.uk/visit

Have a wonderful time!

Jill

It is possible to do the Tower of London in the morning, by lunchtime hurry on over to Westminster Abbey, afterwards go to the V&A Museum and go straight to the jewels exhibit. Then look around the V&A for the time you have left in the afternoon. Then go somewhere for dinner. It can be done if the OP wants.

Again, thanks for all the help. I don't know if everyone understands my question about Oyster card vs cab. What I mean is there are 4 of us traveling together all sharing one cab fare. Is one cab fare more expensive than 4 Oyster trips? I understand how the card works. We used a similar system in Hong Kong.
I think I have a ton of great suggestions to work through. It will be a great trip for sure.

What I mean is there are 4 of us traveling together all sharing one
cab fare. Is one cab fare more expensive than 4 Oyster trips?

Yes. Cab from Bayswater to Westminster Abbey and then the Tower of London will cost more than four tube tickets using Oyster and more importantly will take WAY longer as you will be driving right across London in London traffic.

Enjoy Cathy! We're doing Scotland and then Ireland starting 7/5, and some time in London too.

Study the tube options for your London visit here:

https://tfl.gov.uk/plan-a-journey/

If the weather is decent, the Thames cruise is interesting to do once, and your guests should enjoy that and seeing the subway for the first time.

Bill in SoCal