Questions on Customizing

I'm going to buy buying a rMBP next month, Lord willing. I guess I wan to know form you guys, preferably the high level guys, if the upgrades are worth it for my uses.

I basically use Parallels to manage itunes matches for my friends. I have mutiple virtual machines. I usually don't run more than one at a time. I have an iMac and can leave them on it if necessary but would like to be able to do what I want on my new machine.

I listen and manage my music through iTunes and manage my picutres through aperture. I never game and never intend on gaming. Just don't think it is enjoyable. I do use numbers and pages occasionally for my business but other than pictures, parallels and music that is my biggest thing. Of course I use the web but not like most. I don't watch movies on my computer or anything like that.

What is the best configuration for me? I would rather more storage space if some of the other specs are worth sacrificing. But if they are not then I'll just have to carry around a external hard drive. I can't afford to max everything out and spend 3-5 thousand on a laptop.

Any suggestions would be fine. I currently have an '09 iMac that is intel with a 3 terabyte hard drive that is half full. I know that I can't have one like that through apple in a rMBP. I'm fine with that. I currently have 12 gigs of ram. That I must admit I've never really been able to tell the difference with. Maybe I'm doing something wrong in getting the most out of my ram. I have over 500 gb of music and stories. About 100 gbs of pictures and that is about it.

Thanks for your help.