hi there touring people

i am thinking of purchasing a trek 520 for going on holiday, long rides, camping etc and the occasional commute but no retailers have them on the shop floor for me to pre ride before i buy. therefore i am kind of doing guess work relating to sizes. i have a friend who works for trek who has said to go for the 21 inch rather than the 23 but i ride a 23 bike to work which is a 1970's touring frame converted to singlespeed which is comfortable. i am 5ft 11inches tall with a 32 inside leg what i am asking and hoping i might be able to get some advice about is what sizes other folk ride and if anyone has any specific experience with the 520 that might be of use. any advice would be greatly appreciated.

thanks


jon