[Amaru]

There are 3 "levels" of Contiki tour -- or at least there was when I did my two Contikis (2007, 2009): Budget, Standard, and Premium.

Budget = you'll be taking busses, staying in questionable dorm-style places, and often doing your own dishes and chores and shit. Other peeps on your tour will generally be younger and more likely to get blackout drunk every night. Larger tour groups likely.

Standard = you'll be taking mainly busses but maybe also trains/planes, staying in hostel-type places, and eating adequate food. Other peeps on your tour will be all ages (but primarily 19-25) and have a wide range of party-prone tendencies (nightly blackout to non-drinkers). Medium to large size tour groups likely.

Premium = you'll be taking mainly planes/trains and sometimes busses, staying in decent 2.5-3.5 star hotels (shared rooms possible), and eating decent food. Other peeps on your tour will be all ages and have a wide range of party-prone tendencies (nightly blackout to non-drinkers). Small to medium size tour groups likely.

Different tours and destinations will have different inclusions (ie. some may only offer breakfast while many tours include 3 meals almost every day). Almost all Contiki tours, from what I have heard/experienced, do not include paid activities/excursions... so expect to pay a bit out of pocket to do shit (ie. I paid ~$90 for a tour of Istanbul, paid ~$30 for a walking tour in Hvar, paid ~$60 for an organized dinner out at a restaurant in Athens, etc).

Both my Contiki tours were in Europe, and both were "Premium"...

I thoroughly enjoyed the first one and have nothing but great memories from that trip (10 day Athens / Greek Islands / Turkey cruise)... small group of only ~13 of us. Tour mates were all ages (from 18 to 33) and a nice mix of Aussies, Kiwis, Canadians, Brits, and a few Americans. I enjoyed the mix of sobriety/chill nights and occasional drunken debauchery. Food was generally good.

The second tour had its high points, but wasn't nearly as fun as the first (9-day Croatia / Dalmatian Coast sailing tour). Bigger group of ~20 or so. Tour mates were mainly aged 18-23, mostly Aussie with a few Kiwis/Brits/Canadians and one random Venezuelan chick. Every night was a complete gongshow. Food was OK.

My wife did a 36-day Budget Contiki in 2009 (all around Europe) and described it as "fun but ridiculous" -- she met great people and had some crazy fun times, but they stayed in absolutely garbage places in a few spots, and spent many hours on the bus (often leaving at 7am hung over as fuck). Overall though, for her easygoing and fun-loving personality, it seemed like a good choice and an easy way to see Europe without any planning/worries.

If you're 18-25 years old, lacking travel companions, but seeking some fun and a hassle-free way to see the world, I think Contiki is a great way to go. For a first-timer, you might want to try a shorter Standard or Premium tour to begin your trip, then continue onwards after the tour ends (you'll almost always meet a few cool people on the tour that will want to travel with you afterwards).

To answer one of your first questions, Contiki tours are definitely safe, and in some sketchier places I'd say that's a big plus as they're a big-name tour company with a reputation on the line so they actually give a shit whether you get home safely.

^^ Plz keep in mind that all the above info is 5-7 years out of date, so some things may have changed since then.