I have had my Jeep for about 3 years now and I love it! I haven't had any major mechanical problems so far except for one.
A/C compressor went out twice.
Front passenger side floor wet.
Transmission shifts rough at low speeds.
Sometimes, not always, electric shock when exiting the vehicle.
Weather stripping wear down on the front and rear door of driver's side.
Handbrake does not perform like it should in drive, only in reverse. Needs adjusting?
Alternator went out once.
I plan on keeping my Jeep forever. It is very reliable. For being a 2WD model, it's gotten me out of some serious (here in Texas) mud.
Great vehicle for traveling and off road.
It gets the best of both worlds!
The reason why your floor is wet on the passenger side is because the condensation from the air condition has to run out of a tube that runs behind the floor against the firewall in the passenger side of the jeep. If you pull back to rug, you will see the tub with a rubber grommet covering the hole. Pull out the grommet and unclog the hole of all debris. Your floor will never be wet again :).
This is a common problem with the 98 Grand Cherokees. I had the same problem.