A wood-plank ceiling gives rooms a solid Old World look. Wood ceiling kits are designed to link together via tongue-and-groove fittings on the sides of the boards, like a wood floor. You cut them to size and nail them to the ceiling with a trim nailer, starting at one end of the ceiling and working your way across. The planks have to attach directly to ceiling joists, which means they have to run in a direction perpendicular to the joists so they cross them. If the ceiling isn't stripped to the joists, use an electronic stud-finder to locate and mark all the joists.
A suspended ``drop'' ceiling is a good option if your existing ceiling is at least 8 feet high (since you don't want your new ceiling to be less than 7-1/2 feet high) and the home decor is relatively modern, so it won't look out of place. The big advantage to a drop ceiling is that it simply hides whatever was going on with your original ceiling, meaning you don't have to rip it out, fix it up or do anything else to prepare. Most modern drop-ceiling kits use an aluminum grid system that you put together and attach to the wall, with wire supports up to the original ceiling. Then it's just a matter of popping in the premade ceiling panels.
The simplest way to transform your wavy, cracked or patched ceiling is to cover it with a rough enough textured paint to hide its imperfections. Textured paint is like regular paint, except it has heavy sand or other particulates in it, so that when you roll it on, it takes on a stony, rough look. Stucco is the same general idea, except it's closer to a type of cement, and is applied with a trowel rather than a roller. You use the trowel used to leave lines and ridges in the stucco, giving the ceiling a dramatic texture.