What altitude should I pick when I am flight planning. I know the East/West Odd/Even and VFR +500 rules. That still leaves a lot of options.I am looking for any rules of thumb, tables, formulas, etc. Do any of the flight planning software help in determining what altitude to fly at?I can think of a couple of factors that would affect altitude decisions, such as length of flight, type of aircraft, and weather conditions. But how do you combine these factors into a altitude for a flight plan.Also what are the rules/guidlines for maximum altitude in an unpreasurized airplane, i.e. no oxygen.

Not sure of the flight planning software. You usually want to choose an altitude that has the best, or least-worst WINDS ALOFT. There is nothing like a great tailwind to get you where you are going.As for max altitude, I would still look for the best altitude that has the similar direction I'm flying. I read an article the other day that recommends supplemental O2: Day 10,000ft and Night 5,000ft.I've flown at 7500ft once in a Cessna 172. Made the world seem so small. Hearing some hangar talk, a Cessna 172 pilot really doesn't need to drag the airplane above 10,000.Look at your POH for ballpark figures. Example: a 1979 Cessna 172N will optimally cruise at 122KTAS at 8000ft burning 8.4gph and 10,000ft burning 8.0gph. See how the math works best for a safe flight.Fly Safe.JimPS: I'm not instructor. Consult your instructor and POH for detailed information.