A good intro to the sweetened sours is the Chapeau Geuze, it gets bad reviews online but it's a delicious beer and I think a great intro to the genre.
I also know that drinkstore have a few of them as they got a case in for me recently and I only took six of the twelve bottles.
Mariage Parfait is a more hardcore example not being sweetened.
I'm really getting to like the sours now too and have a project for blending a geuze in mind shortly, I already have the lambic blend yeast bought and will shortly make that into a starter <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt="

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15 Gallons @ 5 Gallons per year and after three years I intend to blend and split it three ways, making a Geuze, a framboise and a Kriek, ambitious but I think it'll be fun.