Some helmet manufacturers make visors that have a coating that helps the rain bead and run off. For all that they are considered an economy helmet, I've found Scorpion visors to be one of the best. At 40+ mph, I can simply turn my head about 30-40 degrees to either side, and the rain runs right off.
Also, I would recommend gloves with a built in squeegee. My Olympia winter gloves have a 3 bladed squeegee built into the thumb, and it works well. For summer gloves, you can get finger squeeees
here (3 pack for $16).
Rain-X is formulated for glass, it does ok on plastic visors, but is not ideal. Honestly, you'll have better luck using Pledge (or similar dusting spray). However, I've found
Visor Proof works much better. And I rode in Seattle for a couple years...I used a lot of that stuff.