Creating a lot of apps have taught me some important lessons.
One being also keep in mind that you may have to translate your app.
I tent to use NSLocalizedString for every string I write in code just so that when its needed I can easily translate the app. Which has been a time saver many times.
I don’t really use the multilingual NIB (adding localised versions of NIB files). Because, especially in early stage if development, you have to maintain two or more files. I just do it in code and adjust the UI if needed.
Getting the size of a string is fast en easy.