Before I get to what I really want to talk about, let's talk about upcycling. Maybe I should start with how much I hate the word "upcycling". Did we really need a hip new word to describe something as common-sense as reusing stuff you've got on hand? Using things you already have on hand is at the heart of making shift.
The Wikipedia entry for upcycling defines it as the "process of converting waste materials or useless products into new materials or products of better quality or for better environmental value". The authors of the book Cradle to Cradle: Remaking the Way We Make Things state that the goal of upcycling is to prevent wasting potentially useful materials by making use of existing ones. These two definitions differ slightly, the first one implying that the materials are made into a higher-quality product. The second definition implies that the already-existing materials can take the place of new materials but makes no value judgment on the "quality" of the materials. This second definition seems to suit my purposes better. I reuse things that already exist in order to avoid using (and buying and maintaining) new materials. My uses of these materials may or may not add value to them but they certainly serve as suitable (and often equal) replacements.
And this brings us to what I really want to talk about. Upcycling in the kitchen. Specifically, I want to talk about drinking glasses and Tupperware containers. A couple of years ago I was rinsing out a glass jar for recycling when I had a revelation. I was about to throw out this perfectly good glass jar, a jar that was the same dimensions as my drinking glasses. And I was running short on drinking glasses. I had planned to buy some more at the thrift store soon. Yes, I was going to recycle the jar, so it would eventually be made into other glass things, but it had only served ONE use thus far. It had held olives or salsa or something else I had bought at the supermarket. It seemed ludicrous that I would cast off exactly the same material I was about to turn around and purchase at a store. And I realized that plastic storage containers (such as Tupperware) are the same story. We throw out or recycle our sour cream and yogurt containers and then turn around and buy the exact same things for storing leftovers in the fridge.
I haven't bought a drinking glass since then and the only storage containers I've bought are a couple of those specialty compartment ones for my kids' lunches. We now have an eclectic assortment of drinking glasses and I think we all have our favorites. I like to use real drinking glasses (not plastic ones) for my kids, even my 3-year old, and when you are using old jars it is not a big deal if one gets broken. In addition to supermarket jars I also hang on to canning jars (Ball and Mason jars), which are especially nice because they have standard sized lids that are easy to replace. Plus, canning jars have a nice heavy feel to them.
If you balk at the idea of using jars as your regular drinking glasses you might still consider using them for your kids for the reasons mentioned above. Jars with lids that seal well also make good water bottles, especially if you don't like using plastic. (And you don't have to limit them to holding water. You can carry homemade tea, smoothies, or anything else in them.)
As far as plastic storage goes, we go through a lot of yogurt around here so I have plenty of large (24-32 oz) yogurt containers to use. I use them for storing leftovers in the fridge but, like all plastic containers, I always transfer the food to a glass dish for reheating in the microwave. I also use yogurt containers for holding bathtub toys, rinsing the shampoo out of kids' hair in the tub, holding cleaning supplies, making sand castles, holding nails and screws, and holding small amounts of chicken feed. They make great scoops. When they get cracked or nasty I recycle them.