Hmm.. wheel spacers. I know people don't necessarily have any problems with them, but to me it's adding complexity to a place you shouldn't have any. In order to check for tightness you have to remove the tires.
Anyway to your point. Are you talking the stock 16 inch wheels? I would be hesitant about them. I'm not sure what the back spacing is on those, and with is possibly too thin, and with adding almost 35" tires you would not be able to upgrade the brakes at all.
Generally, JKs get run with 17" wheels. Better selection of tires for a better price. More options for upgrading brakes.
If you are buying 16 wheels to put on, some of them are not going to be the right bolt pattern. A number of sites mess this up when you filter the results and show both earlier TJ / YJ wheels mixed with JK ones. They do not have the same bolt pattern.