I found an unusual tip this weekend: the Ateco #64, which is considered a star-cut tip. It's a curved petal tip (like you use for piping violets), but it has a couple of teeth carved into the inner curve by the narrow end. The teeth cause whatever you pipe to have a ridge:
I can imagine this tip being useful for borders and swags, but I wanted to try piping a rose with it (only because it looks so much like a violet tip). I started by piping the rose bases in advance and allowing them to firm up. Go here to see why this step is important.
Wilton do that. ;) Seriously, I go sort of nuts thinking about all the angles, hand positions, number of petals, etc. that are involved in piping roses. The basic thing you need to do is pipe a center wraparound petal…
As you can see, these look more or less like traditional roses, but with a grooved edge. This might be the perfect variation for you, if you're tired of piping roses that look like everybody else's. Try piping roses with other non-traditional tips!