I wouldn't begin to even consider trying to convince you that all-day rides are beneficial to you. You've made a fairly strong case, that for you, they are not. In terms of excitement, I've always found that change in what has become a routine is helpful. Take a trip to the Netherlands and ride around Amsterdam for a week or two. (While I suggest this more in jest than anything else, it is symbolic of what I mean by change - something really different.)