There are advantages to half step gearing when running 5 on the back as you get more closely spaced gearing than you would with a larger jump in chain ring size; the downside is that it's complicated and involves a lot of double shifting.
The old fashioned way to figure this out was to do a print out of your gear ratios and tape them on your handlebars.
Also bar end shifters are good here because of the double shifting.
Lastly, for touring you might want to ditch the 36 and go with something more hill friendly like a 28; this will give you a half step and a granny gearing.
By the way, turning this into a 3 x 7 is not difficult. You'll need a longer axle and some spacers plus obviously a new freewheel like this,
http://www.amazon.com/Shimano-MF-TZ3.../dp/B003RLNOKC
The parts aren't expensive but you will have to redish the wheel and spread the frame from 120 mmt to 126 mm.
The shimano mega range of freewheels are interesting because they are fairly closely spaced in the first six (14 to 24 with 2 tooth jumps on the 14-34 freewheel I linked to) with a big jump to the 34 on the rear. This will let you run a bigger gap up front (say a 52-40-28) and still have gears nicely spaced (I haven't done the gear calcs so this is off the top of my head). That way you will avoid all the double shifts as well.