It depends on what you want from your lift. If you are off-roading, the suspension lift is the way to go since that is giving you more ground clearance, and (slightly) more articulation. The body lift is really just for more clearance from the tires to the body so you can fit bigger tires.
As for work load, I would say both lifts are somewhat comparable, just different. I installed a 3" susp lift, and it should take one day, but took two because one of the UCA camber bolts was seized into place and that was a royal PITA to deal with. I just recently added an additional 3" of body lift. Also, kind of a pain in the ass, but it was done in one long day. Getting everything apart and lifting the body itself wasn't that bad, it was more getting all the bumper relocation brakets together and remounting the radiator and things like that. Both are fairly involved, but I would say the susp is truly "bolt-on" where as the body lift requires a little more detail things and some slight cutting of metal.
I would say that a susp lift is practical for off-roading, and a body lift is more just for show. However, a susp lift AND body lift gives you both sides of the coin. For me, I had the susp lift and it was great, but I was running 33s on stock rims and I wanted a wider stance, with more offset rims. I went to 10" rims, with 3.25" offset. They stick out a lot, and I had clearance issues with the body. (bigtime issues up front while turning) So, up the body went! :-)
http://www.haughs.net/memories/2003/haspin/photos/photo_27.html http://www.haughs.net/memories/2003/haspin/photos/photo_11.html Enjoy!