Senator Kennedy was in the Twin Cities. Originally he and Wellstone were scheduled to campaign together in the metro area but Wellstone canceled so he could fly up to Iron Range for a funeral. Kennedy stayed in the cities and Walter Mondale and Warren Spannus (I think Spannus - a former state AG) made the rounds with him. Kennedy was scheduled to meet up with Wellstone later that day for a rally in Duluth.
It has been speculated - and neither Kennedy's nor Wellstone's people ever confirmed or denied it - that they would have flown up to Duluth together had they been able to stick to the original schedule.
I know there is are some pilots who think Conroy (Wellstone's pilot) was not very good but I also know someone whose husband was a commercial pilot and who flew as a passenger with Conroy and thought he was a good pilot (they were also personal friends so that may color his judgment). Conroy had flown Wellstone before and, as both Paul & Sheila were nervous flyers, it seems strange that they hadn't noticed any problems with him in the past or someone didn't clue them in so they could have asked for someone else.
There were also stories from people who lived in the area of the crash of strange goings on. I saw one live report the day of the crash (either on CNN or CBS) where an eye witness claimed he saw a flash from the tail of the plane - that interview was not replayed that I ever saw.
I also had it from a very reliable source that Karl Rove was on the phone with the (Republican) Secretary of State telling her how the already filed absentee ballots in the election should be handled before the public announcement of Wellstone's death was even made and that the opinion that came out her office was clearly written in D.C.