I am a 29 yr. old female who took a Contiki Tour to Turkey.
I had a great time. The standard tour drawbacks do apply - less flexibility and a hectic schedule. However, for getting around a place like Turkey it was great. I got to see several different cities/regions (Istanbul, Gallipoli, Cannakale, Pamukkale, Pergammon, Troy, Ephesus,Antalya, Cappadocia, Ankara)
I was lucky that the people on my tour were cool. I'm actually still in touch with them over 1 year later. The average age was 28 and it was a well-travelled group.
However, speaking to other friends who did their tours in Europe or Australia - I'd say avoid them. The Europe tours tend to attract 18 yr-olds who have never left the US and just want to drink their way thru Europe.
I am considering them again for a trip through Morocco. I figure it's a safe and easy way for a single female to travel through Morocco.
Email me if you want more details.
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I wish I were 1,000 miles away