It depends on how sweet you are looking for.
If you are looking for very sweet than dessert wines are the way to go, a Sauternes or Mustacel will be at least 12% if not higher.
If all you want is a fruitier wine then many German white wines like Rieslings or Gewürztraminers tend to be on the sweet side, sometimes too sweet for many palates.
Slightly less sweet whites are Sauvignon Blancs, Chenin blancs , soaves, the list goes on.
All of these should be above 12% Reds are tough for people with sweet palates, there are red dessert wines out there, and there are sweeter reds
but there's no variety I can think of that
is reliably sweeter.
Roses are often sweet, especially the cheaper ones like White Zinfandel , but those can be low quality.
A good Zinfandel red is a great wine, but not what I'd consider sweet.
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Most fortified wines such as port, Madeira, (sweet) sherry, Commandaria are both very sweet and are very high in alcohol.
Many are in the range of 20% ABV.
I would strongly [pun intended] suggest seeing if she enjoys Port or Madeira.
My personal favourite strong, sweet wine is Elysium Black muscat .
It is so sweet that I commonly have it as dessert in restaurants.
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A little primer on alcohol and sugar in wine.
The lower the alcohol is usually associated with higher acid levels because the grapes are picked less ripe.
Champagne is a good example of this.
To offset the biting acids, winemakers usually add sugar to compensate.
That's why so many low alcohol wines are sweet.
Can you find higher alcohol wines that are sweeter?
Sure, dessert wines come to mind.
Sauternes, Ice Wines, Tokay, Late Harvest wines are sweet with more alcohol.
A lot of mainstream wine brands, like Sutter Home are purposely made sweeter.
Unfortunately, the cheaper the wine, usually the sweeter it is.
Like I always mention here, wine is an adventure that only you can travel.
You need to discover what you like (or your wife in this case).
But I think these are several recommendations that should set you on the path.
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Please consider the sweet and fortified wines of the Rhone with Muscat de Beaumes de Venise being the kind of wine that might give satisfaction allround.
I find that the great house of E. Guigal offers an excellent price/quality/ratio for this wine.
beer.stackexchange.com/users/5816/Peter Point
My favourite wine varietal these days is Portguese Vinho Verde which is a super-sweet white wine.
Two major brands are Sogrape Gazela Vinho Verde at 9% ABV, sugar content 11g/L or Caves Alianca Vinicola De Sangalhos Vinho Verde which is actually 10% ABV, sugar content 14g/L
beer.stackexchange.com/users/6725/Ammar Naseer
Following my personal taste, I would advise these two "meditation" sweet wines: Malvasia delle
Lipari passito DOC (Italy, up to 18%); Samos Muscat
(Grece, around 15%); lighter instead (I'd say below 10%) and very different concept than the above two, Italian Fragolino .
beer.stackexchange.com/users/8580/MattAllegro
appasemiento and rippasso wines from Italy are sweeter due to production method of drying/partially drying the grapes before pressing allowing a richer flavour and keeping alcohol levels as high as regular wine.
beer.stackexchange.com/users/8440/Seamusthedog
My wife loves drinking Moscato and Stella Rosa but they don't intoxicate her. I have to occasionally spike her drinks (obviously knowingly) with whiskey for her to feel a "buzz." Are there any wines that are maybe not as sweet as the 2 mentioned but less dry that provider maybe like a 12 to 15% alcohol content?
Wine recommendation on the sweet side with 12 to 15% alcohol
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<wine><recommendations><red-wine>
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beer.stackexchange.com/users/6693/Andre Hopkins
Many white wines from Germany are sweeter yet high in alcohol. Sauternes, Ice Wines, Tokay, Late Harvest wines are sweet with more alcohol. Appasemiento and rippasso wines from Italy are sweeter due to production method of drying/partially drying the grapes before pressing allowing a richer flavour and keeping alcohol levels as high as regular wine.  Slightly less sweet whites are  Sauvignon Blancs, Chenin blancs  and soaves. Port and Madeira are other options. German white wines such as Reislings or Gewürztraminers are considered to be rather sweet, and Sauvignon Blanc, Chenin Blanc and Soave wines offer a slightly less sweet option. Fortified wines are another suggestion, with varieties including port, madeira and Muscat. Sauternes, ice wines and late harvest wines may also be suitable. Some wines for the mainstream market are purposefully made sweeter, such as Sutter Homes wines, for example. However, some wines, such as the appasemiento and rippasso wines from Italy keep alcohol levels high and intensify flavour by drying the grapes before pressing.
German white wines such as Reislings or Gewürztraminers are considered to be rather sweet, and Sauvignon Blanc, Chenin Blanc and Soave wines offer a slightly less sweet option. Fortified wines such as port, madeira and Muscat are popular suggestions, as well as sauternes, ice wines and late harvest wines. Mainstream brands such as Sutter Home may purposefully be made sweeter. However, some wines, such as the appasemiento and rippasso wines from Italy keep alcohol levels high and intensify flavour by drying the grapes before pressing.