London is fascinating and 8 days is a good amount of time! Even then, you won't see everything on your list.
How to plan a London trip is a matter of personal preference, other here may well have a different view than mine.
Having said this, in general, your 2nd option may be best, your first option possibly may be more trouble planning than the value it gives you. Again, just my personal preference.
But....and just trying to be helpful here, let me respectfully suggest that you might be slightly over-thinking this. Planning is good, but over-planning sometimes backfires, IMHO.
Just one example: Weather and closure days can affect the most carefully laid plan.
And note that many/most London "sights" close by 6pm.
You'll likely be traveling back to your lodging on the Tube, so fatigue, though a factor, isn't going to be as big a factor as if you were walking back to the hotel every night.
The usual tourist sights in London are spread over an enormous geographical area, which is why you'll want to take the Tube or buses, or even taxis occasionally, to cover longer distances and save your energy for walking the sights and between sights located relatively close to each other.
You'll probably want to mostly take the Tube in Zones 1 and 2, these zones are covered by the tube passes and include many of the things you'll want to see, except outlying locations like Greenwich or Kew Gardens. Just try to avoid the Tube during commute hours.
Happy Travels!