After having the watch for a day this is an excellent question and one that I think makes the watch a particularly difficult purchasing decision.
I ordered the 38mm and 42mm SS with black sports band. As many of you know the 42mm here has had some real supply problems but I did get the 38mm yesterday. When I went for my try on I immediately preferred the 42mm and almost cancelled the 38mm, but they had the white sports band at the try on rather than the black. I think that made a difference. Anyway now I have the 38mm it seems perfect.
My point is that this is more than just the size of your wrist, etc. the band can make a difference to whether a specific size will work as well. However there may be other factors, for example I am having a real hard time reading the complications on the watch faces. I probably need reading glasses (turned 47 yesterday), but generally don't have them and obviously would not wear them to look at my watch. I don't know if the 42mm is that much bigger that I would be able to see these better or whether it is just a matter of getting the right brightness etc, we'll see when the other one comes in.
Anyhow, I can really see a need to try out both sizes, with your actual band, for a day or two to make the absolute right decision.
Thanks goodness apple has a good return policy and has got rid of that silly open box restocking fee as with this type of product you have to try it out in real situations not just 15minutes in a store.
My advice to everyone, if you can cover it on your credit card and you are not certain then order both and take your time to get the right one. It's a beautiful product, you want it to be perfect.
I'd post a picture, but I really think the pictures are misleading, you HAVE to try these things yourself and make a decision.
Just my 2c
