I have three groups of items that I keep packed up, ready to go:
1) Electronics. I my laptop bag, I have a power strip, a 1 to 3 multi-tap plug, a small LED flashlight, earphones, Cradlepoint router and Aircard, and all the chargers we need. I usually have several non-electronics things in there too, like ziplocks, a binder clip, a trash bag, etc. This all goes with me anywhere I go (hotel or timeshare).
2) Toiletries. In a small toiletries bag, a good variety of things that I might need. A brush, toothbrush, a variety of OTC sample packs, Doan's, small containers of Advil and Aleve, a variety of band-aids, moleskin and round-pointed scissors, and a quart bag containing all my liquids - cologne, deodorant, toothpaste, shaving gel, etc. This all goes with me anywhere I go.
3) Timeshare boxes (mainly cooking supplies and spices). I've consolidated all of the things that are small, nonperishable and less convenient to buy in the right quantites on the road into a small, sturdy box (that originally held 28 bags of microwave popcorn from Sams) and a comparably sized hard shelled cooler. These two fit easily in a fairly small suitcase with extra room for other things.
The items we have in our timeshare boxes:
Ziplocks (plenty of sandwich, quart and gallon size)
Aluminum Foil
Tupperware containers (other items are packed inside of these)
Plasticware (only if we're going to be entertaining and need extra)
Napkins
Reynolds Oven Bags
Microwave Popcorn
Tea Bags
Kool-Aid Packets
Ketchup/Must/Mayo Packets (we don't use much, so these are more efficient)
Salt & Pepper (hasn't been necessary yet - might remove)
Steak Seasoning
Ranch Seasoning (this, onion soup mix, and gravy mix make an awesome, simple roast)
Bouillon Cubes (we use one cube to season a can of green beans)
Garlic Salt
Taco Seasoning
Lemon Pepper
Onion Soup Mix
Brown Gravy Mix
Cinnamon
Sweetener
Dishwasher Pucks
Laundry Sheets
Liquid Hand Soap (one for each bathroom and the kitchen)
Coffee
Pasta
Jello
Peanut Butter
Jelly (might switch to jelly packets to prevent waste)
Honey