Traffic is not horrendous, and is quite mild in Orange County compared to other major cities. The surface street traffic from the Embassy Suites to the Disneyland parking structure won't be anything to worry about. And compared to I-Drive in Orlando, the Anaheim Resort District is like a sleepy little town with one stoplight.
Are you thinking you want to drive a rental car each morning to the Disneyland Parking Structure or Toy Story Parking Lot? Or are you just going to ride the hotel ART shuttle bus to and from the Embassy Suites. The hotel shuttle drop you off about 75 yards from the theme park entry gates, and that can be much easier than dealing with the parking structure and parking trams and paying for parking each day. An ART bus pass is 2 dollars per day, unless the Embassy Suites has it's own private shuttle bus.
http://www.rideart.org/
And you are sure you don't want to try one of the closer hotels on Harbor where you could just walk a the two or three blocks to the parks?