How to determine what altitude to fly GA?

Excellent stuff Geofa. Really appreciate the info.BTW, I also use the freeware Flight Prep, (not the Pro edition, thus I am not able to use weather into the program via DUATS), for planning my FS routs in the US and some of Canada. I then take that info and create an FS plan.It is a great program, as it does provide you with all the minimums graphically via the vertical profile window, and in addition, accounts for things like MOA's and various class airspace around airports, along with TFR data. Those are things which the default FS planner does not take into account. FlightPrep is a really great program for FS 'pilots' IMO.