The Tour du Mont Blanc is a classic long distance walk in the Alps. Typically taking 7 to 11 days covering a distance of over 167km including 8000m of ascent. The route takes you around the highest mountain massif in western Europe over high passes giving amazing views of the towns, glaciers and mountains as well as passing through alpine valleys, towns and villages giving a feel for local life.
It can undertaken by all types of walkers from hardcore backpackers carrying tents and their worldly possessions to people staying in high class hotels being ferried out daily to walk a section at a time. However it should be remembered that the walk takes place in mountains so you'll need to be physically capable of doing 1000m of ascent virtually everyday, able to deal with quickly changing weather conditions and able to navigate in poor visibility.
If you don't think you can take the challenge on your own there are plenty of good walking companies who will supply all you need.