If the series is released with both English and Japanese audio tracks, my brother and I would usually watch the series in English first. Then I, by myself, would watch it in Japanese all the way through; my brother doesn't like reading subtitles much. I actually want to learn Japanese, and I'm using anime, the internet, and a CD-Rom program to do a self study. I don't have money for a class.
The only series I haven't seen in English with my brother is GTO (Great Teacher Onizuka). I think the English dub is really bad for that one. I mean using Spike's calm, smooth sounding voice (Cowboy Bebop) for the main character (Onizuka, Eikichi) just doesn't work. I doubt anyone here has seen GTO. If so, just ignore this paragraph.
P.S.
Just as advice, if there is a domestic release for an anime, and you want to choose between a big bundle import and a single DVD domestic release, choose the domestic. From experience and also being a non-Japanese speaking person, I can say that most imports are pirated in China and have the worst subtitling ever (getting the Inuyasha series and Perfect Ghibli Box as imports is proof of that). It depends, however, on who releases the series. Although, if you can read Chinese, that's awesome because the imports have really good Chinese subtitles (according to a friend of mine) that are actually on time and not late!!!
