I'm going to weigh in here since I've done pretty much all of the below (not with the National specifically, but a standalone amp) so can share my thoughts.
Get a Sony PHA-1 and use existing iPhone 5
I got the PHA-1. Almost immediately I found it super annoying to swap my iPhone in and out of it. I broke down and bought a dedicated iPod Touch for it. YMMV depending on the amount of times you intend to connect/disconnect in a day. I have to admit now I'm very happy with this setup. It's relatively streamlined compared to a Cypher Labs-based setup. And as an amp, so far I'm happy with the PHA-1. Got mine at B&H for $379 FYI. This is the setup I use most on-the-go since it's easiest to handle. I've found myself using it at home, strangely, when I just want to take a quick 20 mins to listen rather than plug in to the bigger setup. I have two kids (one new) so being able to take those 'stolen moments' is an unexpected use case for me that's really worked out.
Get an ALO International and buy an iPad Mini
Option 2: I already had the iPad Mini but bought the Int'l primarily to be a portable amp to use with computer. Using with Mini is a great bonus, but if you don't already have the Mini it's an investment. I found this setup to be a little annoying trying to find a graceful way to do things like change the music while on the go. The footprint of the Int'l isn't a great match for the iPad if you're trying to handle both simultaneously. To me the value of the Int'l is being able to throw it in my bag easily for a business trip to connect to my laptop, take it to work etc. I have a feeling now the PHA-1 setup's going to supplant that.
Resurrect my old iPod classic, forego an external DAC and go to an ALO National
Cost effective! If you decide later on you want a DAC you might find yourself in a pickle. I tried this setup for a little while, got a cheap used Fiio amp just to see if I liked the setup in principle before getting the National or Continental. Then again, you can easily add the CLAS later on if you don't mind the weight and size. For me the flexibility of having the DAC was key. I imagine moving a National if you change your mind and don't need it wouldn't be hard on Head Fi.
Then there's this:
The lightning to usb cable is suppose to work with the iphone 5 on ios7 (no jailbreak). We will find out this month
I'd love to read more about this, if you have any links to point me to. This sounds really great. The International would work off the bat, it doesn't leech too much power if any from the iDevice--i.e. it already works with the iPad. I just ordered a USB hub that's supposed to get around the iDevices' current power consumption limit. If that worked, and the lighting to USB cable worked with the iPhone 5, I think the iPhone->Lighting/USB cable-->small USB hub-->Dragonfly would be the lightest possible "rig" I could imagine. I live in NYC and would see if that could be my subway rig. I'd also happily strap the Int'l to the phone despite the odd ergonomics.
This is like group therapy. I have to admit, I've been an Apple fan traditionally but the mental gymnastics involved in getting the digital signal out of their devices has pushed my patience.
