Why I don't use fancy planning software
Given the following:
1) I fly VFR
2) The trip is long with several fuel stops.
3) I have GPS map
4) I have fuel totalizer
I have tried some of the planning tools and find them too confining, too many assumptions, too much to learn and inflexible in the face of changing weather.
My planning looks like this now:
1) The night before study the weather from many sources.
2) Along the general route, mark on a IFR low alt chart:
a) cheap (and expensive!) gas
b) interesting stuff to fly over
c) interesting places to stop
3) Pick possible destinations that are a tank away.
This process up to this point doesn't take that long because I haven't spent time trying to be precise. Now I sleep on it and get up early and do the following.
1) Let the morning weather pick my first destination (often different than expected!)
2) Get weather briefing and file.
3) Get sectional(s) ready (course line landmarks) and prefold
4) Program destination in GPS, make sure fuel totalizer is programmed.
5) Write brief notes for probable destination airports.
This process also doesn't take that long. The map folding and notes streamline things in the cockpit but aren't that crucial (day, vfr, cramped RV4). In the air I can get frequency information easily from my GPS, runway/airport info too. I have check points (typically airports since my GPS shows them) marked on the sectional that I follow.
Now I fly the route but plan on being as flexible as possible, not as rigid/pre-planned as possible. I have the sectional on my lap, the totalizer on 'fuel remaining' and the GPS map showing me where I am. I monitor these very carefully. I'm particularly afraid of loosing the GPS and thus SA so I'm comparing the sectional and the GPS carefully. I fly to my probable destination, if the winds are helping or hurting me I will happily land early/late. If the weather is iffy I'll divert.
The fuel totalizer makes it possible to remove much of the math that I used to do. Since the totalizer and the GPS are not connected the only math I do in route is taking the 'duration remaining' from the totalizer and subtracting the 'time to target' from the GPS and making sure that is more than my minimums. That delta (which is effectively 'fuel remaining at destination' is the number I use drive my decision making.
The GPS is also critical for the SA and the text information it provides on runways, altitudes and frequencies.
I always get the weather at my destination en route. It is not uncommon to change destinations en route because things can change in 3-4 hours. The ATC guys have been really good at providing this help.
A word of warning on using fuel price to pick stopping points. I landed in Mott, ND only to find a crop duster strip, far from town, no cell service and a plane in a low fuel condition...Luckily I found a quarter and made the call for the lady to come out, but it took over almost 2 hours and I had no access to flight planning tools other than calling flight service.