My absolute favorite race is the Yukon River 1000 mile race. I finish it in about six days in a voyageur or C4 canoe, other finishers may take several days more and we do not see most on river after the mass start. Second favorite would be the Yukon 440 mile River Quest, closely followed by the Adirondack 90 miler. I have always been greeted at the finish by my very important pit crew, spouses mainly, along with supporting friends, plus race officials. It is not just the physical paddling and "pain" of the longer marathon length races, it is the intense planning, training and team coordination, the efficiency of navigation, best paddling technique in difficult areas and reading odd currents, the unique sights, and all the on race options of critical decision making. A six mile "race" is just a training warm up.
I do several shorter Adirondack regional races as well, especially including the 90 mile Canoe Classic (which is staged over three days). Everyone gets to witness and cheer on each following racer finish until the last one crosses the finish line, and all stay to participate in a variety of awards and have a provided meal in the park. The same is true of most shorter non-marathoon races. Get tired, sure, but it is a good kind of tired, and any little pain does not last long and is well worth the experience.