Originally Posted by Jasonation

An S-class ticket on the same flights is going for $1,485 which is going to be significantly more affordable than one in B class.So in addition to the $1,485 ticket, you’ll need to shell out 25,000 United miles in each direction to upgrade to business class.
This could actually represent a good deal, depending on how much the underlying S-class coach ticket costs.

By redeeming an upgrade instead, you’d be out 50,000 miles and $1,485 for the coach ticket (and you’d still be eligible to earn miles on the ticket).