ACtually, if you have goldies, you will want to clean the gravel at every water change - about once a week or more..... Goldies are incredibly filthy fish - and the waste left in the gravel is all stuff that your biological filter needs to work through. The less you leave it to process, the better the water parameters will be.
That said, it IS difficult to work around real plants in the tank. When I had them, and in other tanks I know of, people purchase relatively small gravel tubes - 1 inch in diameter or so - and carefully work them in and around the plants. If you just gently push them down into the gravel, wiggling the tube very gently, you can remove a trememdous amount of waste without disturbing the plant's roots.
It takes time and patience, but the tank will shine!
Others will plant the plants in individual pots, and then bury the pots into the gravel so they are invisible. When cleaning the pots can be lifted aside and the gravel well vacumned.