I always pack:
A handful of Ziploc bags in Gallon and Quart size....I find them endlessly useful for organizing, storing, packing and throwing away food in the little hotel room garbage cans.
A small Bag with all of the medicines I prefer (ie Tylenol Cold/Flu vs. Advil). I hate spending a day off looking for stuff that I could have packed in a small amount of space...especially when I do not feel well.
Some small item to go on my bedstand.....something to remind me of home. It is the last thing I see at night and the first thing in the morning. I bring a new thing each tour and later these items remind me of the tour.
A small bowl, spoon, small knife, corkscrew and fork. Always keep cereal or granola on hand for those...oops I worked on the schedule until 2 AM and now room service is closed moments.
I carry my books in the roadcase until the end of the tour and then sell them at a local used bookstore. I love this because it means someone else will share my books, I make a little money for the small fortune I have spent on books and frequently I find a wonderful book store where I can buy a book for the plane ride home. The only place I could not do this was London. Oddly, I was informed (by more than one bookstore) that there were no used bookstores in London...only rare book stores which were NOT interested in popular fiction...huh
I generally pack about 2 1/2 - 3 weeks worth of clothes in neutral colors so I can mix and match. I get bored of clothes very easy and this amount keeps me somewhat happy and less likely to buy clothes just for something new instead of something special. NOTHING goes in my suitcase that can only be worn with one other item or that requires special care (ie..handwashing, ironing, dry cleaning). Those items always ended up staying in the suitcase the whole tour so I just stopped packing them. I would rather sightsee in Paris than handwash, iron, or try to find a dry cleaner.
This last tour we were doing 3 & 4 day sit downs. I packed my suitcases by folding and then putting the clothes in vertically. I loved that I could see eveything. I filled in the top with Eagle creek bags with various items (shoes, electronics, socks, etc...). Unpacking/Packing was fast because you just grab the bags off the top and then throw them back on top. When my laundry bag was full it fit easily on top of the depleted stacks and when laundry came back it was easy to slide in the new stacks....I have toured for years and this was the first time I felt happy with the way i had packed.
I am a big fan of the Samsonite carbon 2010 series. They are half hard with a soft top. So, you have structure to protect your wine bottles and wiggle room to throw in the souvenirs...those Ziploc bags are useful for the wine bottles too...Gallon size baby!
And I do still take the Shampoo/Conditioner from the room if they are nice. They are all in a Silver bowl in the Guest room for my guests to pick and choose what they want. I think I have enough to last about ten years

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Happy Traveling - Dani