New Post: N-Tier Application using EF/WPF/Middle Tier

Hi, I have developed 2 tier applications using EF5 (Code First) & WPF that have worked wonderfully. Now I'm planning to develop a bigger application and considering EF running in the Middle Tier. Just trying to figure out what are some popular middle tier technologies that work well with Entity Framework.
I've researched WCF & Web API but wasn't satisfied with the examples I saw. WCF involves mapping entities to DTO which seems inefficient and redundant. Also, not sure about the performance on these either.

Would be great if you can share your experiences or point me to right direction.

Thanks