Well, as far as stairs, Murray is a really long basset with really crooked front legs which bother him from time to time. Stairs are hard for him to navigate, especially going down. So he doesn't go up or down stairs very often. When my husband takes him to school, he rides the elevator with Paul up to the classrooms, and when I take him to the nursing home for pet therapy visits, we do the same. He's a real elevator expert by now- waits patiently for it to come, stands to the side quietly after he enters, then waits til the door is all the way open before he moves forward to leave.
As far as travel, we either bring the dogs with us, or get a student to housesit- neither of our dogs has ever been boarded.
As far as your move to The Netherlands, that sounds like quite a move! I'll be interested to hear how it goes!