Me and the Mrs. have had this debate a few times. She rides a beach cruiser, and our last outing was pretty one sided with me on my Voyageur. We don't try to set any speed records, but it was obvious that she was doing a lot more work than I was, and in the long run the comfort you gain from seating position is more than offset by the extra effort you put into hill climbing and fighting wind. That said, I am looking into a more upright stem, but I think the seating position of a road bike will give you the leg leverage advantage, and a taller bar height/rise will improve the comfort level. You should be able to find a good compromise between the two.