Thinking about aspect ratio is actually a move in the right direction, but you shouldn't really be thinking of aspect ratio per se, rather than the overall layout. My suggestion is the following.
First, try not to think of resolutions. Think of the screen layout and how many layouts you will support. If you have iPad, try to look at it vertically and horizontally.Try to imagine if iPad was shorter but longer (e.g. being a widescreen). Try to draw the organization layout on paper thinking where you will put your game's elements depending on the screen orientation and shape (e.g. closer to 4:3 or closer to 16:9).
Once you have the proper organization strategy, one important issue is how will you handle different DPI settings. For instance, you may want to include large icons and resize them to smaller versions on the fly to take advantage of high DPI displays and make the game look similar on different devices. Another alternative would be putting more elements with higher DPI settings, so instead of bigger icons, the user will see more of them. You can even try some hybrid approach as well.
If you plan your game's conceptual organization on different layouts (vertical/horizontal) and shapes (4:3, widescreen), properly handling different DPI settings, you will make the majority of your users happy. As you can see, this way you are not thinking of resolutions and aspect ratios, and you are not using vectors, procedural content and other stuff, which is not related here anyway. This is the best non-intrusive approach, which in many ways is enforced when you develop for iPhone/iPad, even though it perfectly applies to Windows/Mac OS systems.
In order to properly solve a problem, instead trying to fix the problem itself, you should change the conditions accordingly so the problem ceases to exist. You may want to check
this article, which is more of philosophical nature, but still applies here.
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