Each year for the last 15 years or so, I have been traveling to Europe on tours lasting from 5 days to 6 weeks.  Each time I pack just about the same amount of stuff into my bags.  Here are some tips I have for packing for your next tour:

Carry-On, Don't Check:  I would say that for one reason or another, about 10% of bags are lost or misdirected. This can be a disaster and ruin a vacation.  Probably the only time I do check a bag is on my trip home because if the bag is lost or misdirected, it really won't affect my trip.  I also take a photo of my checked bag so that if it is lost or misdirected, I can provide the photo to baggage services for easier identification by them.

Put Anything That Might Be Flagged By Security in a Separate Hand-Carry Bag: Think about what you need to get off your body when going through security - watches, metal jewelry, glasses, phones, wallets, coins.  Then think about what needs to be taken out of your luggage - your liquids stored in small bags.  Then think about what might get flagged in your luggage - electronics, wires, metal.   BEFORE going through security pack all of this in separate plastics bags and put it all in ONE larger plastic bag.  Remove that one bag and put it in the tray.  You will find everything much easier to manage and find.   The real problem comes in when "flaggable" items are put in a larger piece of luggage.  If it is indeed flagged, you will need to empty EVERYTHING out for inspection - if you have ever flown through LHR you know what I mean.

Light Shoes:  I always pack at least one pair of shoes when traveling.  I love Skechers 

Plastic Bags:  I can't tell you how useful they are for packing shoes and separating my dirty/clean laundry.

Buy this Carry-On Bag:  I love the eBags line of luggage.  They are light, priced right, expandable, the right size and protect my valuables.  I have gone through a lot of different pieces of luggage, and I like this one the best.