As for storage, get at least a 1TB hard drive. SSD drives are still rather pricey, although having one can make even an older computer seem like new. When the price of SSDs gets more reasonable, I will probably upgrade. Also, if you want quick boot time, a hybrid drive is a good choice. I recently replaced the 500 GB drive in my MacBook Pro to a 1 TB drive. I took the 500 GB drive and put it in an external case, so it hasn't gone to waste. My Dell XPS 17 (L702X) (has the i7 processor), which has 2 drive bays (plus a DVD/BluRay optical drive), has the 750 hybrid drive as the main hard drive, and I added an extra 500 GB drive that I had hanging around. I have a thing about having enough storage space. Call me OCD about storage space.
Getting a laptop that is upgradable, even if it is only replacing hard drives and adding memory, is a good idea because it can extend the life of the computer. That way, it can grow with you. Storage space and memory are really not expensive. Although I love Macs, my one objection to the retina MacBook Pros is that they are not upgradable, otherwise they are a nice machine, although rather pricey.