Cafe Crema isn’t exactly next door to WWDC but its fairly close and some people might be staying near that part of town for WWDC. It has really good coffee and breakfasts that don’t come in a box and sit waiting for several hours at the conference center!
And after some coffee and breakfast, it’s an easy 25 minutes walk to the convention center.
If coming from the direction of the Whole Foods, the first thing you will notice is the mural,
It is fairly close to the Whole Foods and the CalTrain direction (unfortunately in the wrong side of the station for myself) but it does has lots of parking in the back. Plus generous number of tables and spaces to seat inside.