With those big lanterns and the stonework at the base of the arch planters are going to create clutter. Instead, line each side of the walkway intermittently with simple solar lights at the ground level, shining across the brick walkway. In between you could plant small pools of flowers, or just grow low ground cover over the entire side space to fill it all in. I'd even consider juniper. Whatever works for your climate zone and your appetite for gardening.

I see round terracotta or neutral shade planters spaced around the sides. Similar to this picture with the hedge. A hedge or round planters would work. Creates a walkway, cozies up the space and the planters won't be engulfed by the large size of the house. A pot on each side would quickly become an eye sore because of the vast space you have in the landscape.

If possible change the lights out, they're not doing much for the structure and might be a bit large/droopy. If they have to stay, paint them up in a brass or gold color to get rid of the dull look.

I don't see the need for planters here and think you are going to get cluttered. But if you are set, I would get a concrete or stone that matches the color of the archway and square or rectangular.