Air supsension kits - newbie

I'm eyeballing several used 3/4 ton chevy's right now.  I'll probably end up with one between an 2004 or 2006.  I know that right off the bat I want to tweak a couple things, but I'm concerned about ride/functionality.  I lean towards chevy's but dislike their height and the size of tires when compared to competitors.  So, I would like to put 17 inch rims on to help in that department and because I will be using it to work and pull good size loads (fertilizer trailers/ cattle trailers) I would like to install air bag suspension.  I have several questions for some of you guys who have experience.  I'm not wanting to gain a crazy amount of height because I know that can really mess with handling/ride/etc.  Ideally I would like to gain around 3 inches (no, 'thats what she said' jokes please) through tires and suspension without sacrificing comfort.  Can this be done with what I'm looking at?  Will adding air bag suspension only give me a lift from standard height if I have the bags pretty firm, thus giving up comfortable ride?  Thanks in advance  

i have 2" level kit with 2" spacers on bags with no rear lift on my 01 hd 285-75-16 fit with minor unnoticble work to back fender well i run 30 psiu in bags unloaded and 90 with slide on in just till a buy new springs with rear lift built in i kept 2" rake looks good and hight is nice but not top heave a little bouncy with 90 psi but unloaded rides like stock but camper had beat the rear springs in well before but i like the ride on bags you only should run 5 psi if lift is all done and air up close to empty ride when loaded so ride should not change lift then bag to save springs don't bag to lift and your all set here is pics of camper on and off copy and paste link to view
http://viewmorepics.myspace.com/index.cfm?fuseaction=user.viewPicture&friendID=427982333&albumId=1408641  

ther are suspension lifts now for 3" all the way around for these truck when i did mine I could only find 4" and 6" lifts and wanted low cog for camper but be cautious of blocks most kits have lift blocks in rear and for towing I would find a spring shop the guy near me said $600 and he would build them and would still have to add like one or two leaf which will stiffen ride a bit but Camper weighs 2500lbs empty and sits in bed so I figure enough trips bouncing down beach it will settle in and ride good