I've been on a real potted orchid kick lately-they're sculptural and incredibly gorgeous, adding so much life and prettiness to any room you put them in, and I've also found that they're surprisingly accessible (and affordable) at many a big box retailer. They stay in bloom for weeks, if not a couple months, which is far longer than most cut flowers, which last for about six or seven days, tops. Orchids also tend to be very low maintenance though there are a few general tips one should be aware of to help make them last:
The most common mistake people make with orchids is over-watering. Part of the beauty of these guys is they only need to be watered every two to three weeks. Proper drainage is essential too, so you never want the orchid to stand in water, since the dampness will kill the roots. If you notice leaves are wrinkling, you're probably over or under watering your plant. To check, tip the plant over and examine the roots. If they're white, tan, or spread out all over the soil, you're probably not giving it enough water. If roots are mushy and brown, you're overwatering. In this case, trim the roots and repot the orchid in fresh soil.
Prune them regularly. If you see any yellow or brown leaves, snip them off. Same goes for dried up blooms.
Orchids like humidity-therefore, kitchens and bathrooms are great places to put them (and from a design perspective, they work really well in those spots too, adding life to areas with hard tiled surfaces).
Plants need adequate light in order to flower properly. It's good to keep orchids close to natural light/windows (rather on a coffee table in the center of a room) though also beware of too much harsh direct sunlight (which will be obvious if orchid blooms start to shrivel up and yellow). Make sure the orchid gets at least a couple hours of sun each day in the morning and afternoon
Don't put an orchid too close to a heating or air conditioning vent-the big temperature fluctuations don't make for great growing conditions.
Fertilize your orchid once a month with a 30-10-10 orchid fertilizer. You only need a bit though-half the suggested amount is probably fine.
Once all the flowers are gone, cut the orchid stems off at about the fourth node up from the base. You can expect the flowers to re-bloom over time, though most of the time, the fewer flowers will reappear after each time you cut.