I think players can appreciate the beauty and complexity of the Planescape adventures more if they're used judiciously and are interwoven with "normal" adventures adapted to the setting. As I mentioned earlier, my heroes are currently going through The Great Modron March, but that requires the modrons to make it ALL the way around the Great Ring...that takes a lot of time, and the adventure has a lot of gaps between detailed scenarios. I've filled in the holes with a combination of homebrew and published adventures adapted to fit. Some examples:
The heroes visited an alternate material plane world where dwarves were the most common race, and humans extremely rare...they helped a dwarven king break an old family curse. ("In the Dwarven King's Court" from Dungeon Magazine)
The heroes visited a world where humans were nearly extinct, thanks to a new species of sentient plant that was restoring the planet to its "natural" state. (The Forest Oracle, a 1E module; it was this adventure that introduced the adu'ja and t'kel player character races from Dragon Magazine to my campaign.)
The heroes accompanied the party's paladin to Mount Celestia for him to become a Fist of Raziel, and became embroiled in a train heist in Erackinor (the realm of Moradin and Berronar). ("Train of Events," from Dungeon Magazine)
The heroes journeyed to Graz'zt's realm of Azzagrat to rescue the Master Trader. (For Duty and Deity, a 2E Forgotten Realms adventure; I substituted the Master Trader for the kidnapped goddess.)
The heroes journeyed to the asian kingdom of Tatsukatsukai on Bytopia to sell the Abyssal bloodiron they acquired in Azzagrat. (Homebrew adventure where the heroes ran into the adu'ja again, making them regret not taking action against the plant people earlier in the campaign.)
As it is now, the heroes have only made it to the Sylvania scenario, where I substituted one of the player characters for the good doctor's experiment victim. There's still a LONG way for the modrons to go before The Great Modron March is finished.