Thanks for sharing your thought process. I have to say I've been thinking about it a lot because it's not your typical buy/don't buy decision and the additional variable of selling the BWV as part of this transaction complicated things in my mind (and here on the boards too).
While the sale of your BWV did not make RIV any less expensive (the price you paid was absolute regardless of how you came about the money), it did offset the cost of upgrading your DVC portfolio and in that regard, it does have a valid application to the equation. Basically the way I've framed it to better make sense is to make it binary. You could either have option 1 or option 2 below:
Option 1:
22 years of use on existing BWV contract
$21,000 cash in your pocket
Option 2:
50 years of use on new RIV contract
Blue card for whole family
11 month advantage at another resort
This is basically how it breaks down and from that point it becomes a personal decision as to which you prefer. Clearly you chose option 2, and congrats on your decision!