Options for what to put in the center:
Yin Yang, Celtic Knot, Lotus Flower, Symbol of some sort (chinese, tribal, rune, etc.) a Terrified looking feeder fish, a heart made of bubbles (or something "watery" lookin)
i'd leave it ....nothing in the centre, unless you have a sprog and put its name in it....because thats like so original.
i guess asians are more boxy looking lol but the colour has to be sexier than a silver....are you colouring it?
If you like the rose, then leave the rose. I like the rose and water lilly both personally. I wouldn't add color except for the shading on the rose. Leave tattoo green outlines with red shading. I think it would look sweet!