The first conference I want to point you guys to is PFCongres. PFCongres is organized by Dutch PHP and web development community PFZ, in which I recently became an active member by joining their events committee. The PFCongres will take place on Saturday September 17th in The Netherlands, and I would highly recommend submitting to this conference because of it's variety in topics, levels and delegates that you'll find here. I've been a speaker in previous years so you can trust me when I say that they take care of their speakers :)
The second conference is one everyone knows. It is widely seen as THE PHP conference in the world. Of course, I'm talking about ZendCon. Santa Clara will again be the home of this year's ZendCon, which has Cloud Computing, Mobile and User Experience and Exterprise and Professional PHP as the key themes. As you can see from the topics, make sure to submit some more advanced topics to the CfP. Want some tips and tricks on submitting to ZendCon? Read this post by Kevin Schroeder.