The last bit - I know this has been long, but only in an effort to be helpful.
The tube. You know, not a crazy as I remembered. The Circle Line required a bit of deciphering, but once again, the strategically located, helpful staff were happy to give clueless tourists some guidance.
Heathrow. We took the Heathrow Express, which was easy as we were near Paddington Station. Quick, clean, and not crowded at all. The airport was also better than I remembered, with lots of gate space, pre-gate seating, food options and window shopping.
What made the biggest impression on us were the English people at all of the tourist sights. Across the board, they were exceedingly kind, delightful and helpful. Another example -- the elevator in our flat was not working and the third floor walk-up was a challenge at the end of a day, but to the owner’s credit, he volunteered to carry our luggage to and from the apartment, even coming out at 0800 on our departure morning despite the fact that he had earlier said he wasn’t available until after 11. But, less so the tourists. Lots of pushing and line cutting to be had.
It’s clear that we need to schedule another trip soon. London, of course, is endlessly entertaining and impossible in such a short time. It was such a good experience that we'd like to see more of the country. We had some rocky moments for sure, but overall it was great and we’d go again in a heartbeat.