Depending on your level, new planes become available to you, and new destinations! Below is a list of all planes and levels at which these can be purchased:
  
Swallow — level 1

Swift — level 5

Owl — level 7

Hawk — level 13

Raven — level 19

Eagle — level 25

Jumbo — level 31

Giant — level 41

Falcon — level 51

Thunderbird — level 61

Condor — level 71