In addition to the Southern realignment fully taking place in 1994, in Northern and Western suburbs the Democrats got killed by Clinton's tax increases (in 1992, he campaigned on a middle class tax cut, but with the huge deficit, chose to simply increase taxes on the rich), gun control, the stimulus that was proposed in 1993, and the health care debacle was hugely embarrassing.
Going with the Southern angel of American politics, despite Clinton and Gore both being from the South, they culturally identified with the liberal wing of the Democratic Party, unlike Carter, where being liberal hadn't quite become a negative things yet.
Cultural issues were also a big, big theme during not just 1994, but all of the 1980s and 1990s. The Democrats happened to be on the wrong side of a lot of those issues when the electorate was far more culturally conservative on abortion, guns, and gays (anyone remember how Hawaii almost legalized gay marriage in 1993 by the courts? True story).
40 years of Democratic control of the House led to a lot of complacency amongst Democrats, and when a bunch of scandals appeared in the early 1990s, the Democrats were hit hardest (being in control).
The Democrats were definitely NOT pro-gay in the 90's at all, Clinton signed DADT and hardly any democrat spoke in support of gays. Really it wasn't until around 2006 or 2008 that Democrats really started being supportive of gays. '
The other issues (abortion, gun control, and healthcare) were largely the reasons the realignment happened in the South and West. There really weren't many House seats lost in the North at all (there were a few). I think Clinton's Federal Assault Weapons Ban in 94 was particularly unpopular in Western states.
