Flying Thru Congested Areas

"O. Sami Saydjari" The shortest route would take
me straight over the top of
Detroit and Clevland and Pittsburg (I am flying from Central Wisconsin
to Washington D.C. to be specific).
I'm not familiar with this route but did you do a great circle route *and*
plot the actual great circle route on the chart to determine the
'conflicts'? I assume you are using a GPS to fly and it will follow the
great circle route using direct routing but it is not always obvious what
that line looks like on the chart unless you plot a few points. A fuel or
rest stop can change the entire equation once fuel prices are factored in.
Perhaps this is a no brainer, but
that does not sound like a particularly good route to me, just because
of the congrestion in these spaces. The congestion (a) increases the
likelihood of vectoring delays, and (b) decreases my safety somewhat
because the probability of a collision is somewhat higher (although,
still quite small, I realize).
The big question here is IFR or VFR. IFR you take your chances with regard
to routing. You can influence it but not control it. OTOH, you get more
help in reducing the probablility of a collision. Depending on weather, IFR
may be the only way or the optimal way depending on the weather. Or VFR may
be the way to stay out of the weather. If weather offers a choice, I find
IFR often easier on such flights because of the help in airspace management
(TFRs, Restricted, etc) and I prefer to fly at IFR altitudes with maximum
ATC involvement.
If I pick a route to the south, I could avoid all of these areas by
about 30 miles, but it adds about 60-70 miles to my trip. Even at 30
miles south, I imagine the congestion will be significant. In fact, a
controller once implied that it is often better to go straight across
the top of a major airport because there are fewer airplanes in
transition there (descending for approach, or climbing for departure).

So, what do you folks suggest? Thanks in advance for you advice.

If you are IFR capable, planning a VFR flight, but without a lot of
experience flying such flights, fly IFR and use it as a learn-the-system
experience. That's the only way to really figure out the best way to do
such a flight in the future