Organized trips for young single travelers? [closed]

I have 3 weeks vacation during Sep-Oct.

I'm an Israeli with excellent English. I want to fly somewhere.

and was thinking to join organized trips for young single-travelers.

I saw this site:

http://thedragontrip.com/

http://www.vodkatrain.com/Journeys/default.aspx --> I pass this one. Too short for every city.

Does someone know to recommend this one or suggest any familiar other?

Update:

A more detailed request:

Where do you want to go? You've mentioned Vodka train - so are you keen for just Russia? If you could narrow down the countries you're after, and the things you'd like to do, we'd be happy to offer some suggestions

I'm 27. Like urban travels, but enjoy nature as well.

Less interested in museums (only few in a trip). Mainly monuments, interesting buildings (Love architecture). Absorbing local culture by walking through the city.

I love to see as much as sight-sees as possible.

I love to walk a lot. Thought to use couch-surfing.

Plan to travel alone, so I though joining a group could be nice (but this is not a must).

Not restricted to a specific area.

I get 3 weeks vacation from work during Sep-Oct 12. I thought to use the relatively long vacation to get further away than nearby Europe (but Europe is still an option)

Does anyone know of organized tours for the age of 20-30? (I am 27).

Have been to central Europe, Thailand, USA.

Wanted to visit central America, but I think trans-Atlantic flight are to expensive for such a sort trip.