Yes, Guiness has a lower alcohol content. In general sweeter more tasty beers have less alcohol because less of the sugars from the hops and barley are converted to alcohol, thus leaving more flavor. Of course its more complicated than that, with recycled enzyming and stuff.
Funny, "Coors Light isn't beer" but you like Killian's which is brewed by Coors. Personally, I think Killian's sucks when compared to a red Irish ale.
Weihenstephaner Weisse Bier, Salvator, Tusker, Moosehead, and Franziskaner are my favs.