It all depends on score, clock, field position, and teams in question, so any generalizations would be wrong in a lot of cases, but in general, in my humble opinion...
2nd and short is often a deep passing/play action down (since you have third down to pick up the first, assuming you can run reliably)
3rd and long is a passing down since running it is unlikely to pick up the first. However, you'll see real teams calling draw plays fairly often with 5-8 to go... It always annoys me when I watch games because they seem to never work. Also if you're running clock, the 40+ seconds might be worth more than a first down to you, in which case it's a running down.
3rd and short is a running down. But it's also a good place for play action since they'll have to respect the run.
1st or 2nd and more than 10 is often a short passing down.
Your mileage may vary.