To the OP:
I had that EXACT color and type of gravel in my last 60 gallon goldfish setup (did you get it at Petsmart and was it the "Top Fin" house brand of blue gravel?)...we did a "pirate shipwreck" theme, which would go good with the "pirate barrel" decor you have in there now...I also had similar plastic plants like yours...
I am in the midst of re-setting up our 60 gallon (after it was wiped out by a bacterial infection) and decided to go with a more "natural" theme, adding a large "tree stump" decoration to the left, natural-colored gravel, etc...we're also trying to incorporate an "Asian" theme with this, being that we're goldfish fanatics, but it's been real hard; since the tank is cycling, we're doing the decorating in very small stages (for budgetary reasons too)...
If you want to keep what you have, drop in a cool-looking shipwreck ornament and perhaps a small skull with the pirate hat on; I think it would go good with your theme.