Personally, I don't think you'll notice much difference in image quality between a 1080p 22" or 24" screen. As for viewing distance, I think you'll generally find something that's comfortable for you. Go with your feeling there, it'll be more accurate than trying to science it. Yes, 'science' is a verb. I just made it so.
Take into account all your other preferences, and see what monitors are left at the end of thinning down your selection. If it's a 22" panel, that's great. If it's a 24" panel, that's great too! If it's down between a 22" and a 24" panel, pick what you think works best for you.
I use a BenQ GL2460HM bought from Amazon Italia (yep, I'm italian too) at less than 160€. 24'' 1080p 60Hz. I use Virtual Super Resolution (Radeon Crimson drivers) to reach 1440p without problems. Might want to check it out