I have heard nothing but good things about Tauck Tours but if you were looking for something a little more economical (first class as opposed to super deluxe) I can recommend Insight Vacations (blue book). They have a number of different tours from which to chose and although not as relaxing as cruising, the pace is acceptable for one-country touring. Their tour guides are very knowledgeable and are very well organised. We went with Insight around Europe last year and hope to do a "Country Road" type tour one day. Whatever you decide on - have a fabulous time and be sure to visit Venice for me - I loved it!