I don't have any specific product I want to push on you, but I do want to mention one thing. Your speakers (including, of course, the subwoofer) will affect the sound more than anything else. I have speakers, including subwoofers, that retail for over $6000, and I was using a receiver that retailed for about $600 with them. I recently upgraded to a receiver that retails for about $1600 because I wanted some features that I did not have. But they sound the same. (If my speakers were more inefficient, or harder to drive, it could have improved the sound, as the new receiver will put out about twice the power of the older one, but I did not need more power, so the extra power is irrelevant.)
My advice is to listen to as many speakers as you can stand to listen to, and as many types of speakers (e.g., horns, ribbons, planar, cones, etc.) as you can find. Once you have them selected, then you will need to figure out what kind of amplification you need. If you end up with speakers that are normal efficiency and normal impedance, you probably won't need a separate amplifier at all.
As for room treatments, I would probably budget that money for better speakers, unless there was a particular problem with my room that desperately needed to be corrected.