To add to that, probably the last standout convention battle we experienced was Ford v. Reagan in the mid-70s. As DT states, the primaries are so pre-selecting exeercises that the conventions have become simply one step in the nominationprocess.
The last convention of any consequence was the 1980 GOP convention when Reagan's team was trying to hash out a deal with Gerald Ford to be his running mate. Except Ford was asking for too many concessions (i.e. Power), whether it be re-appointing Kissinger as Secretary of State or nominating Greenspan for the Treasury. Thus George Bush got the gig.
I do sorta miss the conventions, because sometimes you had some unpredictable results. (Wendell Wilkie is one notable example.)
