pre-TBC instances have been pretty much tank'n'spank, with little fear, movement, aggro resets, etc. Its in the TBC instances where they really upped it a notch, and heroics, and probably WOTLK. TBH i had no real issues with any instance in any comp until auchenei crypts (OMG i hate that first boss), last boss of hellfire ramparts (extremely easy mode with shamans, tear-your-hair-out-ridiculous with other classes), black morass (the timer just make things frantic), shadow lab (2nd boss especially, and even murmur) and magisters terrace.

Its really heroics where things will get nuts, any mob that gets off the tank will 1 shot anyone else in your party. Some heroics are fairly easy, some are very difficult.

But definitely interested in hearing how you tackle that stuff, its great practice for WOTLK instancing.