Questions and Answers

Here’s a Excel worthy comparison of miles only award bookings and cash with mile upgrade:

BA: SEA-LHR-NBO, with outbound stopover at LHR in December 2017 for 2 people

CW, fare class “I”; with AARP $400 of pp, & Signature CC 10% off = $9842
F, net of AARP & CC 10% = $17670

Cents/Avio
Miles only, F: 340000 Avios, companion voucher, $3596
Unearned CW Avios 72282 (1 gold & 1 blue member)
Net of CC earned Avios 10788
$ saving: 17670-3596 = 14074
Net Avios used = 401494
Avio = $0.0351

Miles & Cash
Mile upgrade to F: 180000 Avios
Net of earned CW Avios 72282 (1 gold & 1 blue member)
Net of CC earned Avios 29526
$ saving: 17670-9842 = 6246
Net Avios used = 78192
Avio = $0.1001

Other factors:
Cancellation fee
Tier point
Avio balance
Cashflow

What would Lucky do?

Wow! I actually make Excel files like this as well to determine where I should use points and it is an inexact science. You also didn’t account for the money in your pocket to spend in NBO and LOAN once you arrive. I would put it like this

(a) is $6333 worth it to you to spend 160K less avios ($9842-$3596, upgrade vs straight redemption)
(b) would you rather save you avios and pay out of pocket knowing you will have to use them in the future and BA could devalue before you redeem.

I would always go with and say that $6K in my pocket is better than 160k avios in my account, but that is just my 2 cents