I will say I agree with you 100%! I loved Deep Impact, but thought that Armaggedon sucked and was unrealistic, especially the Paris Explosion.
I thought the explosion of Baltimore in The Sum of All Fears was the most realistic I've seen. Usually people wanna slow it down so it can be longer and the audience can see everything explode.
The Tidal Wave in Deep Impact was real as well, especially for the fact that it actually moved fast like it's supposed to. However, the tidal wave didn't do what it would've in real life.
Usually, the asteroid would hit the water in a big splash, but wouldn't exactly create a tidal wave instantly. Instead, you would see the Tidal wave about 3-500 feet from the shore of the land it'll hit, and it would slowly grow bigger and bigger. This is due to the Continental Shelf and the astroid creates a sort of underwater wave instead of a surface wave and when the bottom goes up to meet the land, so does the wave and the water would rise up creating death and destruction.
Btw, has anyone seen the show on the Discovery Channel "Three Minutes to Impact"? It had an awesome scene where Tokyo is hit by a massive Tidal Wave, complete with a choir song in the background to create a mood for destruction.