This one's a bit of a no-brainer, but it occurred to me suddenly, so maybe you're missing the big picture too.
I hate using plastic bags, but sometimes they are the best thing for what I'm trying to do. An oiled Ziploc, for instance, is the best thing for storing pizza dough. A snack bag, overturned, is a good, reusable cover for the Spam can. I always wash and reuse plastic bags until they spring a hole, and then they go into the trash. Drying them is made easier by the use of this device.
You know how TV chefs always tell you to marinate your steaks or pork in a Ziploc bag? Well, I've been doing that, and then throwing out the bag because I didn't trust myself to get it pristine and sanitary again.
Today I needed to marinate a couple of steaks and I decided that I just wasn't going to waste a plastic bag on them. Enter one of my smaller casseroles, in which I mixed up the marinade, and then I covered it with a small platter that's roughly the same size, and voila! I feel like such a dummy because I have covered casseroles, but the trick is to match the size of the container to what you're marinating so that you don't need as much marinade. Also make sure that it's non-reactive, so the food doesn't pick up a funny taste from the acid in your marinade.
If you have a covered serving dish in with your good china, I bet you could use that as well, as long as everything fit in it.
Just for the record, this marinade was a couple of tablespoons red wine, a tablespoon Maggi (or use soy sauce), 3-4 tablespoons olive oil, 3-4 mashed garlic cloves with the skins removed, and a couple of freshly crushed allspice berries. The steaks marinated two and a half hours (don't forget to turn them) and were cooked in unsalted butter, with salt and pepper on top.
While they were cooling their jets on a warmed platter, I deglazed the pan with a splash of Scotch, which I then flamed. Once the flames died down I poured the sauce over the steaks. They were good. No, they were great.
Why Scotch? It is very roughly the same flavor as cognac. In fact, during the French revolution, when you couldn't get cognac out of France anymore, the illicit distillations from Highland stills became the rage, and the fact that you couldn't get cognac helped Scotch whisky's cause. It's not cognac, and you have to use quality stuff (and not the peaty, smoky stuff, although if I had some, I'd experiment with it), but it works in a pinch.