Not that I think this is or should be set in stone, but the original JPL plan for exploring a new world is (or is it was now?) as follows:

Flyby
Orbit
Land
Rover and/or Balloons
Humans arrive
Planet used as construction material for Dyson Shell :^)

It makes sense to flyby first in terms of you don't want to land something somwhere if you don't know what the surface conditions are like first at least to some degree. Knowing what the surrounding space environment is like can be a plus, too. A smashed lander, years of scientists' careers wasted, and cranky congress-types and taxpayers can result from this.

For example, Mars was thought to have a thicker atmosphere than what Mariner 4 discovered in 1965. Some of the Soviet robot landers sent to the Red Planet pre-Mariner 4 had their parachutes designed based on the old (and consequently wrong) data. So, even if they had succeeded in making it all the way to the fourth world from Sol, the Soviet landers would have crashed due to their parachutes being designed for more air than there actually was there.