One can tour the presidential palace (for free) and learn about the interesting heritage and culture of the city. You can also use this as a stepping stone for flights to the Galapagos Islands.
As to which airline should you chose? Copa Airlines is cheaper but credits less miles and the flights are on Boeing 737s with recliner seats. Avianca allows you to fly with lie-flat seats to Bogota and gives a bit more miles so could work better as a more relaxing trip...
Copa Airlines Boeing 737-800 Business Class
Avianca Airbus 320 Business Class