I overfilter all of my tanks, and instead of using one huge one, on my 29 gallon, I have a 30gallon filter AND a 20 gallon flter, one on either side. That way, I can change the cartridges at different times, and always have a filter running. I also use two different brands, as they are slightly different, and I'll bet each one has their strong points, so together I'm sure they cover all the bases. Both of these filters aerate the water as well, but I still have a small pump and airstone in the tank as well. I am all about overkill, I like my fish to stay nice and happy!
Oh, and as far as what size tank should you get... no matter what you get, you will want bigger, that's just the nature of the game! I would say around a 200 gallon should do it! LOL!