The other option rather than over trousers is just waterproof trousers. I use Páramo Cascada 1 trousers, they aren't light, but they are waterproof and very comfortable. No need to keep donning and removing over trousers when the rain happens. Just wear them all day every day and stay dry.
The down side is that in summer they are quite warm. In summer I use Craghopper Kiwi pro stretch trousers, they aren't water proof, but they keep out light showers, and when they get wet they dry very quick. But when it's not hot weather, my Cascada 1's are my goto walking trouser.
J