Made some bourbon maple syrup last night, and it is awesome!! Very simple too - I looked every several recipes, and found too many had too LITTLE bourbon for my liking, and wound up customizing the one I found a bit.
Below is what I did:
8 oz pure maple syrup
1.5 teaspoons of brown sugar
4 oz of bourbon (I used AAA 10 Star)
1/2 teaspoon of vanilla extract
Mix all ingredients into a small pot and bring to a boil (stirring to dissolve the brown sugar). Once brought to a boil, reduce heat to low and let simmer for 15 minutes (no need to stir throughout, although I gave it a stir once or twice during). Then turn off heat but leave pot on the stove to allow to cool (took about an hour). By this time, I had just under 9 ounces of bourbon maple syrup. It should be refrigerated (my original pure maple syrup called for refrigeration after opening, but several of the recipes called for this, so I'd recommend that just to be safe).
I used the syrup on some pumpkin spice pancakes, and it was awesome. My wife says it is WAY too "bourbony" (and the original recipe I found called for only 2 ounces of bourbon), but - I like it that way :-) You can always try with 2 ounces, and if you're satisfied stop there (although I'd reduce the simmer time to 10 minutes).