The backbone of container gardening
Aside from unlimited styles, pots come in sizes from 2" to large enough to hold a tree. The key is to find a pot that's appropriate for your needs. If you plan to move plants indoors for winter you'll want something light enough to not irritate you when the time comes. If the plants are spoiled little critters that demand heat, you'll want something dark that absorbs the sun's rays. You definitely want pots that will hold up in the climate conditions you're gardening in. Unless temporary is a key to your gardening style.
If the container you're longing to use doesn't quite work, take heart. Copper boilers rarely have drainage holes, but they are excellent for hiding plastic pots that do. Just put some gravel or other porous material in the bottom to help keep the plants moist but not swimming. If it absorbs too much heat consider using it in a shady spot. And if it's ugly but all you've got, plant trailing plants to hide it.