The Merchant Princes series: It's like Amber, but it's sci-fi masquerading as fantasy instead of the other way around. It's like A Song of Ice and Fire crashing into The Sum of All Fears, except with more likeable characters and less horrible politics. It's really, really good science fiction.

The Bloodline Feud is close to perfect. It starts as a silly fantasy story about a tech reporter in the post-9/11 USA discovering she belongs to a secret family of princes with the ability for interdimensional travel. Then it explores the consequences of what exactly this entails, and how it all could come crashing down. Intrigue, politics, economics, culture shock, and a really well thought out science fiction story beneath a surface coating of fantasy. I cannot recommend it enough.