Out of the brands you mentioned, Acoustech is the only decent speaker. The other ones (most notably Theater Research) are known as "White Van" speakers. They look cool, but are actually made with garbage components and marked up like 1000%. Stay away from those.
Acoustech on the other hand is made by BIC, a company that has been making quality speakers for 25 years.
Regarding Bose, you are indeed correct. They have an amazing marketing department. Unfortunately they spend way more on marketing than product engineering. Their products are very overpriced relative to the performance they offer. Their drivers are cheap, their enclosures thin and generally not well braced. You can get a lot more performance from a non-Bose system for the same amount of money.
The JBL northridge series is not too impressive, IMHO. JBL has made a lot of good stuff over the years, and in their professional lines, they still have a lot of great offerings. Unfortunately, their lower end consumer lines just don't offer as much performance and sound quality as other brands for the same price. Yamaha is a good option, and since you already have some Yamahas, you might want to check out their offerings. That is, assuming you like the sound.
When buying a HT package, it isn't necessary to get one with a sub, but many times you can save money. In your budget catagory, you'd probably do best to find a package that includes a subwoofer. Of all the brands you mentioned, I would say an Acoustech system would be your best bet. You have a good sized room, so you're going to need some speakers that can fill it up. The Acoustechs are very efficient, so they won't stress your receiver as much when you crank it up. The Acoustech sub is also a good unit. Not as powerful as more expensive offerings, but for the price, you'd be hard pressed to beat it.
