A:Answer The 38mm size is for someone with smaller wrists. The 42mm is for those who like a larger watch face or larger wrist size.
The size is more of a personal preference. You really need to try on both sizes and then decide.
The advantage to the 42mm is it's larger in regards to texting, pictures, icons, etc. So for older eyes or for someone that has difficulty seeing, this could be a factor.
I had a Series 1 38mm and upgraded to Series II a week ago, solely so I could "gift" the Series I to my daughter. She wanted one so bad but couldn't afford it. So I seriously considered upgrading to a 42mm as a girlfriend of mine had one and I liked the bigger face, much easier to read. However, I have small wrists and it just was WAY too big for me. Had it not been for that, I would have paid the extra $30 and got it.