I have the Billsteins on my 04' WJ with the upcountry springs. The ride is firm more so than smooth but it ain't bad for a Jeep. Besides the shocks and springs, also take a look at the tires you are running.
Generally speaking a P tire will ride better than an LT and all seasons better than an AT or MT. My 04' use to have LT BF Goodrich ATs, which are great tires if you need the extra traction and load handling. However, switching over to Michelin Latitudes in P size made a world of difference in the smoothness of the ride. I recently replaced the Pirreli Scorpion ATs on the wife's 01' WJ with a set of BFG Long Trails and although they won't win any awards for offroad driving, they are a very smooth riding street tire with pretty good wet/snow traction.
Here's a like to an online store selling the Billsteins for Grands. Not saying this is the best price or place but it will give you an idea of what they cost.