A little more on Wizofoz's post (and apologies in advance for gross plagiarism from Kermode's
Mechanics of Flight and other excellent P of F texts):
If you want long range, you'll have a good cruise CL/CD ratio.
If you want long endurance, you'll have a good maximum CL/CD ratio.
If you want to get there fast, you'll have a low minimum CD.
If you want to take-off and land slowly (read short runways), you'll have a high maximum CL.
If you want to fly fast, you'll use low-bypass turbojets with highly swept wings.
If you want to fly efficiently over a wide range of speeds, you'll use high-bypass turbofans with mildly swept wings.
If you want to fly at very high speed at 80,000'+ over Communist SAM operators, you'll have maybe 70° wing sweep, huge zero bypass turbojets, and a fleet of air-to-air tankers. (Couldn't resist that one.)
If you want to take-off and land slowly, you'll have really big heavy high lift devices.
If you want to cruise as efficiently as possible, you'll have the cleanest lightest wing possible with very simple high lift devices.
If you want your passengers to feel comfortable, you'll have a big cabin with big windows.
If you want to save fuel, you'll have a slender cabin with small windows.
No doubt you can imagine some more "ifs". I'm sure John Farley can add lots, and probably correct some of mine too!
And lastly, if you want to have fun, you'll fly a two seat aerobatic trainer. But that's off the topic.
More seriously chornedsnorkack, which of the above do you want? All of them? Then you'll understand the dilemma of a vice president at Boeing or Airbus.
HTH,
O8
(PS - one last one. If you want to actually sell your aeroplane, you'll avoid radical solutions because airlines don't like them, you'll avoid "bleeding edge" technology because no-one understands the implications, and you'll take a variety of trade-offs between efficiency and cost. Hopefully you'll sell slightly more aeroplanes than your competitor, at a slightly lower price.)