Not sure whether you are referring to a flight plan with ATC or a the
kind of plan you do to estimate headings, times, and fuel for planning
purposes.

I never file VFR. Often file IFR.

Almost always fly for travel and usually have someone on the other end
curious about when to pick us up. So, I'm always interested in at least
how long it will take to get there. With the winds on ADDS, I love to
plan the optimal altitude for favorable winds. The accuracy is amazing
and the findings sometimes surprising (e.g. headwinds being
substantially less at 8,000 than at 6,000 on a given day). $3.50 fuel
and a slow plane make the exercise valuable on even 1 hour flights.

GPS makes heading calcs unneccessary. Duats provides accurate winds and
dead reckoning flight plans. GPS groundspeed allows detailed wind
soundings during the climb. Again, amazing how accurate ADDS winds are.

Major victory flying Raleigh NC to Tampa FL non-stop both ways last
weekend. Planned IFR both legs with 1 stop. Detailed wind information,
10 mins of cloud flying, range extenders, and a sleeping passenger
allowed non-stoppers of 4.5 and 5 hours (it was worth it).

Michael 182 wrote:
I'm kind of curious - does anyone with more than 100 hours do a flight plan,
with winds and all, before they fly cross country? Most of my planning is of
the fuel stop, or occasionally detour for weather variety - but it is rare
for me to include more than one or two waypoints in my "plan", and I almost
never file an airway, even when I file ifr. Maybe it's because I live in the
west. A typical flight plan will be Longmont - Amarillo - Austin, or if the
winds are good, Longmont - Austin. What do others do?

Michael