There is a cost-efficient way to travel around Europe regardless of months or years of stay. The answer is simple, have an automobile. It saves you a lot from train tickets and taxi fares. One can even go from one country to another at it is own convenient time.
For example, in Switzerland, one could visit the Augusta Raurica, the most Swiss archaeological site that is near the Rhine River. If one follows the said river, one can find himself either in Liechtenstein or in Austria.
Nevertheless, before going any further two things must be considered: inspect completely your vehicle and see to it that it has a mechanical breakdown insurance.