I like To Tuscany, partly because it has a tremendous range of villas, and partly because (unlike many companies) it has an excellent website that provides what you really want when choosing a villa.
Our accommodation, which cost less than £800 for the week, is in a converted stone farmhouse next to a 12th Century Franciscan chapel. There is a pergola shaded by vines round the back here we quickly settle into a rhythm of eating long pasta suppers while the shadows lengthen.