We are flying in to Luxembourg for a Rick Steve's tour that starts in Trier, Germany. What is the best way to connect?
There is a direct bus line between Findel airport and downtown Trier.
If you're not arriving at a convenient time for the direct bus, take a Luxembourg city bus to the railway station and get a train from there to Trier. There are also bookable shuttles but they're pretty expensive.
The train is easy, comfortable and convenient. If I had flown all the way from the US west coast to Luxembourg, I'd want to stretch my legs a bit and take every opportunity to not be stuck in another seat for a couple more hours. I'd catch the connection to the city, take a walk and enjoy the sights (it's an interesting little city, and a great way to ease into Europe), then jump on the train to Trier - much better opportunities to be comfortable and stretch out a bit on a train rather than a bus. Sounds like a nice way to start a European trip to me.