Warrior/Warden/Druid would be nice like you said, you can have 3 viable end game classes. However this would be extremely expensive and you would have to gear all three classes if you want to tank/DPS/heal.
Warrior/Warden/Rogue is nice, you can test out the difference yourself of a Warrior/Warden and a Warrior/Rogue.
Warrior/Warden/Scout is a good choice as well. You can wear the same DPS gear as your Warrior/Warden on Warden/Scout and you get to play a different class without the expense of a second set of gear.
Firetruck W/Wdn/S 72/72/72- Retired as well now...
Bangsalot K/S/R 70/70/68 - Retired
Heretic- Reni