I've been in Luxembourg this summer and I can only advise anyone who likes the country side to have a few days there. You can easily ride all day long and smell pure nature.
If you want to switch scenario it only takes a few minutes to get into the centre of town.
The capital city isn't hard to reach and accessible within minutes.
For those of you that like to see other countries, you can easily reach Belgium, France and Germany as well. You don't need to use a car for that either.
Honestly a great country for long cycles.