I like the hydrangeas on the cake in this link (I couldn't get a direct link). If you click on floral cakes it's at the very bottom on the left. It enlarges if you click on it.

Love the look. I was thinking a rose tip, maybe. Any tips on the movement of the tip when piping the icing?

http://www.cupcakecafe-nyc.com/?KMLID=6140

I did a video on these but it's kind of hard to see.
http://www.youtube.com/watch?v=ZsmnkezYsP8&feature=channel_page

I used a tip 102 and without hardly moving my hand I piped the petals. I kind of piled them up but you could mound the frosting and pipe them on top