DC/DC Converter

[BadCoding]

I am new to power supply issues and need some advice. I have dealt with a linear regulator and that is fine, but wastes a lot of power. I am looking into a switching power circuit as they are way more efficient. To step it up another notch I also want to be able to use two different levels of input voltage.
I need a 3.3V power supply and would like to run the system on some 3.6 lithium cells I have and a 9V batter when we get in a pinch. Turns out there is a ton of information out there and having trouble narrowing it down. Anyone have a schematic laying around?

[k-ww]

Look at the MCP1253 from microchip 2v to 5.5V input, 120mA output -

I use it to convert 3v thru 5v to 3.3 for a project.

Put a 78L05 regulator in front of it for operation from a higher voltage,
or just use 2 AA batteries when the LION one poops out.

The maxim MAX1555 is a good chip to use to charge the LION cell from
a 5V wall wort. - even has a 'charged' indicator output.