Traveling with textbooks
Have you considered using ebooks in situations where they're available and reasonably priced (and don't have Digital Rights Management)?  

A few years ago when I went to Los Angeles for a sabbatical leave, I made it a point to get electronic copies of as many of my frequently used books as possible.  I bought a few, but mostly I was able to work with freely available copies.  This dramatically reduced the number of printed books that I had to take with me.