you're about 5'10". going by the charts and what a lot of people your height ride, PRELIMINARILY speaking, you should be on a 17.5" or a 19". since you want a more upright position, i suggest the 19" because it'll have higher handlebars. you'll have less seat post sticking out so your saddle should not be drastically higher than the handlebar. for you i suggest handlebars level with saddle or higher (rivendell's philosophy on comfort). high handlebars due to the geometry itself and frame size and NOT a radical stem angle or risers is key to comfort. high handlebars + longer ETT is more comfortable than lower handlebars and shorter ETT imo even if they have the same reach.
also, it's nice to have *some* curve (you don't need a whole lot) like a bridge on your back so your back can withstand occasional jolts of off road riding. imo 29ers do not have tried and tested geometry. the geometry is unconventional and different from what we're used to. sometimes specs or what others are riding do not translate what is best for our individual bodies.
be aware of your ball park size 17.5 or more likely a 19" or maybe even check out a 21". then go test ride both sizes for several different models. i encourage you to try other mfrs and geometries too. make sure the bikes are properly adjusted. test ride them. get multiple opinions from the lbs's around you. and then decide. imo, this is the single and only way to figure out the best size for a 29er. 29er sizing seems to be less about the charts because we are still figuring all that out.
good luck! :thumbsup:
