1. It is NEVER a good idea to go to Costco on Saturday afternoon, no matter how fun it may sound. Then again, getting through the glut at the Costco gate should be deterrent enough– but of course it hasn't been, which is why this note needs to be written. Only the most psychotic, scary, and Costco-hungry segment of the population ever shops there consistently on Saturday afternoons. The first time I went (for there was an idiotic follow-up occasion), I was eight months pregnant and WAS NEARLY RUN OVER in the parking lot. This should give you an idea of the kind of Dante-esque Thunderdome Costco can be on Saturdays. Just stay away and save yourselves.
2. It is also NEVER EVER a good idea to get in the way of the poor souls gathering their weekly provisions at any and all area supermarkets on Sunday afternoons. I feel I must be especially cautionary in regards to Whole Foods because you DO NOT get in the way of yuppies and their overpriced foods: I'm sure they will either cut you or sue you for emotional distress.
3. A specific DC don't: never decide to come back into the District from Northern Virginia after 4 pm (but really more like after 2 pm). The hours of agony stuck on the 14th street bridge are not worth whatever was on sale at Target or at World Market.
4. Finally, never make the mistake of thinking that your average-looking liquor store will carry liqueurs or anything beyond a couple of types of beer and wine, and a few strong spirits. If you walk in and ask, they will try to sell you cheap gin and then they will look at you funny.
This is all for now. Carry on with your evening and avoid the DINKs at all costs.