Vacation packages are separate from talking to the normal agents. They are just trying to get you to add on.
Delta vacations is what used to be NW Vacations. There you are looking at packages upfront. Costs, schedules vs the normal booking on DL.com are sometimes better, sometimes not, then what you could do booking flights and hotels/cars separately. You just have to try a wide set of choices.
Much harder to do since Delta crippled many of the previous search options, ie, hotels for only part of the trip.