I will be on the Belgium and Holland tour next year. At some point would a day trip to Luxenbourg be feasible? Highly suggested? Day trips to other towns during the tour? Perhaps add on an extra day at the end to see sights not covered?
I don’t see how you’d have time to do a day trip to Luxembourg during the tour. If this is important to you I’d plan to come in a few days before the tour start.
I also don’t see how you’d visit other cities. There is a full day free in Bruges but I used it seeing the sights there as did most others on my particular tour.
I’d definitely add a day or more to the end for more time in Amsterdam.
Where are you flying in to? Asking to see how you might structure a pre-tour visit.