Here are some of our favorite sites we are relying on to book airport transports or tours. If you considering to travel alone check our comparison of companies that offer small group tours without charing you more.
I have done several tours with GAdventures. They are specializing on small group adventures. I like the combination of small groups, flexibility and organized transportation. GAdventures offers over 600 tours in 113 different countries. I highly recommend the company.
Intrepid is very similar to GAdventures. I traveled with Intrepid several times as well and always made good experiences. They offer almost 700 tours in 113 countries.
As a great alternative to taxis Uber is now available in 57 countries already. I like the convenience and the fact that it is usually cheaper than taking a cab.
Supershuttle's shared Van's are a cheaper alternative to taking a taxi to the airport. I used them across the US as well as in France and enjoy the convenience over public transportation.