I will start by saying that some of the suggestions by people have been good, but I would like to chime in here for a second in order to hopefully shed a bit more detailed light on the situation. Number one, if your wife is like mine, she hates change. This is just a fact with some people. My wife currently has a Blackberry and has tried my phone but didn't like it because of the touch screen. Habits die hard, so I would encourage her that you can make her happy with a few changes if she is willing to let you take a day to do some adjustments on her S3.
In order to accomplish what she wants you would have to install a custom launcher. I prefer Nova Launcher, but Go Launcher has more available themes which will help the look and feel she is looking for. Go Launcher will in no way make her S3 lesser of a phone or more complicated. If anything it will make things more suited to her needs. If she wants the phone to be an exact duplicate of the iPhone then you are never going to make her happy, but with a few tweaks you should be able to set up her phone to operate very close to the experience she wants and still allow her to take advantage of the big screen. If you are not willing to make some of these changes you should return the phone and get her a iPhone 5.
Go Launcher:
https://forums.androidcentral.com/e....launcherex&feature=nav_result&token=ch0W5JUh
1. She wants to see previews of her messages on the lock screen.
The only way she can have her messages viewable on the lock screen is to buy a Nexus 4 or to disable the lock screen and use Go SMS. Go SMS is a free app that works well with the GO Launcher and allows the pop up messaging. If she wants the lock screen on then she would need to slide to unlock the screen if she wants to see it. Go SMS also has an iPhone theme which will be perfectly suited to what she is used to. Installation is simple. and you can download the iPhone theme and change it in the settings options.
Get Go SMS:
https://forums.androidcentral.com/e...jb.gosms&feature=search_result&token=yKrPvOWC
iPhone Theme:
https://forums.androidcentral.com/e...b3Ntc3Byby50aGVtZS5pcGhvbmUiXQ&token=ubKrcKSo..
2. She wants an easy way to put the phone on silent or vibrate (she really misses the hard toggle on iOS).
Download "silent toggle widget" it is a small button that switches from on to silent to vibrate by just clicking it. It's excellent. Or if she wants more toggle options I would suggest the Go Switch widget or Widgetsoid. These allow you to customize multiple options for turning off wifi, data, bluetooth, sync, volume/vibrate/silent etc.
Get Silent Toggle widget:
https://forums.androidcentral.com/e...W0uc2lsZW50dG9nZ2xld2lkZ2V0Il0&token=_EWAjMbY.
Get Go Switch:
https://forums.androidcentral.com/e...chwidget&feature=search_result&token=2edJkehp..
Get Widgetsoid:
https://forums.androidcentral.com/e...251bGwsMSwxLDEsImNvbS5qaW0yIl0&token=lkEv3dTU.
3. She hates having multiple home screens. She wants to just have 1 or 2 with a grid of apps and nothing else.
If you install Go Launcher or Nova you can limit the number of screens.
4. She doesn't like the dot that shows where your finger was.
You can turn this off or customize it in Go Launcher or Nova.
5. She doesn't like having g chat on the phone. Can it be deleted?
Delete the icon if it's on her screen and don't set it up and you should be fine. You may also be able to disable it in your app settings.
6. She finds the phone to generally be confusing with so many settings menus. Is there a way to have a single settings screen that covers everything like iPhone?
Remove anything from the screens that she is not using. When you install Go Launcher you will have a bunch of suggested Go apps that are not installed. You can just delete these from the screen. You can basically start fresh and remove anything that you don't like.
As for the general settings. They are in one section for the overall portion of the phone which is similar to the iPhone settings area. This is accessed from the notification area or the app drawer. But as others have mentioned, each app does allow further control which can be helpful if you want to change something. If she is not wanting to change anything then just leave things as default and ignore them.
Basically, she wants an iPhone with a bigger screen and has no interest in extra features, but she doesn't want to install too many apps or 3rd party tweaks.
This is a difficult one. She can't expect a completely different device to be exactly like her old device unless she is willing to make some adjustments. It's like buying a Lexus and saying you wish you had a your old BMW. Go launcher has themes that mimic the iPhone look and feel so you can download them and try different themes. Your original stock Touchwiz look and feel is not effected by what you install in Go launcher, so if after playing with Go Launcher you don't like the results you can always uninstall it and go back to the stock Touchwiz launcher and carry on.
Here are some iPhone Themes you can check out, but you can also search for more in the play store:
https://forums.androidcentral.com/e...Rldi5pcGhvbmUuZ29sYXVuY2hlciJd&token=gCBpxYMl
https://forums.androidcentral.com/e...C50aGVtZS5waXplcm9leGFtcGxlIl0&token=vFU96JOA.
https://forums.androidcentral.com/e...C50aGVtZS52YWppcmEuaXBob25lIl0&token=KnjxQ_zE.
I hope this helps a little and I wish you the best of luck.