Flying Thru Congested Areas

I am planning a long cross country where I am trying to minmiize the
time the trip will take (while, of course, trying to be as safe as
possible). 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). 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).

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.

-Sami
N2057M
Piper Turbo Arrow III