My family used to rent a villa in Italy every summer and we would go somewhere different every year - and i think it is the best. It is not such a big country so you can be in the stunning rural country side but you can take lots of day trips. We stayed in Umbria a few times, near Todi which is between Rome and Florence and then we also went to a place called Rada in the Chianti region of Tuscany which was near Siena and also not far from Pisa and Florence.
We live in London but we would always drive there, going through France and Switzerland and stopping off in different places on the way. Europe is really great for that sort of trip.
I have also been to Spain which is normally better weather in the south but the food is not as good. The south of France is great fun but SOOO expensive.
I hope that helps. Have fun.