There are hundreds of different types of shower curtain rod designs and shapes. Wooden rods and plastic rods are usually straight, but metal rods come in all different shapes, colors and designs. They also often have different types of connections to the wall than plastic and wooden models. Depending on what type of bathtub or shower you have, you will have a huge range of different things to pick. For any unique shower or bathtub, your best bet is to start with metal rods, and if you happen to find a wooden or plastic rod, go with that one.
For a standard bathtub, you have hundreds of types of rods to choose from.
The standard rubber grips and plastic poles are so common that it is often only the types of shower curtain holders that people are familiar with. One of the new things that has come out with bathroom decor is the curved shower rod. These are curved in a crescent shape to give you some more space to move around in while standing in the shower. There are also double curtain rods that have a rod for the curtain and a rod for the towels. These also even come in curved models.
For stand up showers, there are even more options. There are corner bars with varying angles. There are l-shaped bars that give you a lot of options for different shower stall types. There are also short simple straight poles that are smaller than bathtub versions which make it easy to pick different shower curtains for your shower stall. You can even find claw foot tub shower enclosures that will let you wrap a shower completely around the tub. Those are also usually made of metal, and they will be a good way to keep the water off your bathroom floor.