What should I know before getting in-dash Navigation?

I am purchasing a 2010 Chevy Malibu next month and I am wanting to install in-dash navigation with bluetooth. The reason being is I'm driving from St. Louis, MO to Portland, OR in August by myself and want to have the most reliable navigation. I don't want to have to read a map, since I'll be alone, and I cannot rely on my IPhone navigation because I have Sprint and who knows when I'll lose service driving half way across the country. I am not a fan of things mounted on my windshield or sitting on top of my dash. Hence the reason for in-dash. Since I've been researching different systems, I keep seeing lots of them saying the navigation works only with IPhone apps, like Garmin or Telenav. That would defeat the purpose of purchasing this. Are there any good systems with built-in navigation that does not require an app? It would be even better if I could find one that I could even program a specific route into. I also have to have bluetooth and one that I can plug my IPhone into. I want to be able to make wireless calls, direct Siri and stream audio while I'm driving. Any suggestions will be appreciated. Also, don't be a sarcastic a**hole. I don't know why people are sarcastic a**holes on this site. It's annoying and I'll just ignore your answer.