Ha, so basically the opposite of inobtrusive! ;)
So, you mention HT, "wife," and "entertain" so I assume this means at the two of you, if not another couple of people occassionally. It makes a difference...more people mean more are sitting off-axis in less ideal seats.
You mention music, "not reference", but not whether the movies/TV are all chick flicks and documentaries or are action movies. I'll assume it includes action movies due to your being here and interested in the subwoofer too. Of course, it's hard to judge how you'll like a volume level when one has mainly heard distorted speakers and amps trying to play louder than they could handle. Just like I could say that after trying to fly in a small rickety small plane, I know for sure that obviously going faster, like in a jetliner, could only be worse, right? :)
You've gotten good advice on subwoofage. I'm always looking for more in my basement theater that's open to other parts of basement, and the stairwell to the upstairs!
Can't go wrong with Power Sound Audio that they recommended to you. I have an SVS from 2004 and I just built a DIY sub, which isn't too difficult, esp. with a flat-pack where I just have to glue and clamp wood and install the driver. (I'll put mine behind a wall, but you'd have to paint).
For the center, just note that...
- for more off-axis seating positions, the center speaker is more important, and it's more difficult to do without it.
- 70-80% of TV/movie content will come from this speaker.
- not just dialogue, but sound effects, music, explosion, and gun shots.
So, if you're not just a "two speaker stereo music guy," the center should be equally or more capable than the floorstanders.
If you buy front-left-and-right speakers with 7" woofers, you should get a big honkin' center to match!