How much does Delta Comfort+ cost? Is it worth paying extra?

The price isn’t fixed. It usually depends on:

• Flight length and route
• Travel date and demand
• Your fare type and SkyMiles status (Medallion members may get free or discounted upgrades, depending on availability)

On short domestic flights it tends to be a modest add-on, while on long flights it costs more. My tip is to compare the price at booking and again in Manage Trip, because it can change. More on Delta Comfort+ price is here.