Perhaps water with a small amount of alcohol would have a noticeable pleasant flavor. (but be useless for intoxication)

Indeed. There's a drink called a "White Rain" some friends of mine invented in college:

Start with a half standard Conn Hall measure of either vodka or pure grain alcohol (this measure is approximately 1.5 shots) - fill the rest of the cup (about 12 ounces) with water. Sprinkle in a half teaspoon of sugar, and watch the interplay between the alcohol, dissolving sugar, and water. Enjoy before the liquid calms down.

It's pretty good, and tastes mostly like really refreshing water. Note: the measurements above are best guesses, as the original recipe is based on the cups at Conn Hall at SCSU. If it tastes like cough syurp, you did something wrong.