I went on the Luxembourg tour in Oct 2012 and thought it was pretty good as I hadn't been to that country before. However, it's a long bus ride there and back, leaving little time for exploration on own's own. When we arrived in Luxembourg, I wanted to find out the meeting point to catch the return bus back but the PD told me I couldn't find out until after the mandatory lunch so this wasted at least another hour of our brief stay. During the guided walking tour part, the Unesco World Heritage site of Casemates was passed, but not really noted as a site for a more thorough visit, which I later figured out on my own and returned for the paid entrance. I also went on the Baden Baden excusion which allows very little time for a visit to the baths, although I managed to have about 30 minutes in the beautiful old facility. For such a brief stay, it's quite expensive, about 23 euros. This tour would be much better if the Black Forest part (and mandatory black forest cake eating) could be eliminated, allowing more time at Baden Baden, which is a delightful little town with several bathing options. If you go to the new bath/spa facility, bathing suits are required, so be prepared to buy one if you don't have one with you. The old facility had no such requirement and is a truly lovely site with many different exquisite and recommendable pools. As mentioned in a previous post, the chair lift in Boppard is worthwhile for the view and the lovely walk back down to the boat. This isn't an optional tour, just easy to find about a 5 -10 minute walk from the boat, although if you choose to walk down from the top, it's about an hours leisurely walk. I would think Sept or Oct would be preferable to August as it probably wouldn't as hot or crowded.