If you’re at the limit for the middle capital gains bracket because of one-time gains and you can afford to wait, you should definitely defer liquidating assets to the following tax year.

Yeah this is important for planning, and it becomes even more complicated when you're trying to optimize with AMT involved, reclaiming credits, etc. These things require multi-year planning, and the expected tax bracket is a significant factor.

Scenario 1: If you believe that your marginal tax rate after retirement will be higher than your marginal tax rate now, you would prefer to max out your Roth than you pre-tax now. Many people in tech will be taxed at the top income rate now and at the top income rate in retirement as well; it seems likely that tax rates will have to rise in the future as we're obviously not running a sustainable balance of federal inflows and outflows now.

Scenario 2: If you want to funnel as much money as possible into your employer's plan, you might want to use a Roth vehicle to do that. (Your pre-payment of taxes on it means that $100 in a Roth is worth more than $100 in a pre-tax vehicle.) Your 401k plan might not support mega backdoor 401k contributions (many plans don't allow after-tax contributions [distinct from Roth]) and you might have other IRAs that would drag in the pro-rata rule for backdoor IRA contributions.