I travel for work a lot! I'm a business traveler, so my list is different than yours. Here are my essentials:

Various herbal and black teas.
Gym shoes/clothes for the hotel gym and taking long city walks.
Headphones.
Sleep mask.
Ear plugs.
Benadryl, melatonin, and Valerian (sleep aids, combatting time zone changes on the night before a big presentation is no joke).
Good books and music.
Livescribe pen. (I call this my SpyPen. AMAZING piece of technology)
All of my habitual soaps. (for awhile I was being lazy and using hotel soaps. bad plan.)
Tons of snacks. (I'm vegan, and sometimes the boardroom has no food for me. I bring energy bars, instant oatmeal, peanut butter, and apples usually.)
Laptop.
Garment Steamer.
Lint roller.
Brief case, small purse, carry on luggage.

And most importantly, I find time to do at least one fun non-work thing on almost all business trips. Essential to well being. Usually I visit a long lost friend from high school or college.

Happy travels!