How about a 'coffee table' book?
Maybe one of America? With beautiful scenes from our country?
Or maybe one about trees? I found a lovely 'coffee table' book called "The Meaning of Trees".
Or one of famous pieces of art?
Scented candles? Aromatherapy candles? Fancy beeswax candles?
In the United States generally a good dinner gift is a bottle of wine, but you already mentioned being hesitant about carrying that.
Fancy herbs or tea in sachets? Oooh! Check with Starbucks for teas.
Tasteful music CDs. (Pure Moods, Classical, etc)
Photo Albums. (traditional or digital)
Native American gifts (sandstone art, ceramics, blankets)
Puzzles, boardgames, cards, chess, etc
Sounds like a fun trip!