When we first installed the rain chains, the chain on the south side of the house could easily drain into a rain barrel since it would only have to handle run off from the porch. On the north side though, we had to place a large drain in the flower bed since the runoff would come from the full length of the house. We found the most attractive drain cover we could but it was still large and plastic.
I surrounded it with river rocks (which helped tremendously with splashes and overflows) and planted as close to it as I could. One year later, it almost looks good!