Start by sizing a subwoofer to the room. That will tell you how much money you have left over for speakers. Next choose the speakers based on your personal taste. Speakers are very subjective. But also keep in mind that while a bright speaker like Klipsch can sound really good when you first start listening, some people find the bright sound fatiguing after a while. That's why you'll want to plan an extended listening test at real world (for you) volumes.
Only after you choose your speakers will you want to select a receiver. The primary consideration is will it drive the speakers that you chose, and does it have the features that you want.
In a room that size you'll probably be looking at $600-800 for a subwoofer but I'd draw up a room diagram and then contact SVSound, Hsu Research, and Epik and have them size it.
That should leave you about $600-800 for speakers. Three good options for fronts are 1)
OneCall has the long discontinued Boston Acoustics VR3 towers bundled with the matched VR3 center for $810 shipped. The VR3s are rear ported and need some space. 2) Ascend
Sierra-1 bookshelves for $700-850/pr. 3) Usher
S-520 bookshelves ($400/pr) however the Ushers do
require a subwoofer and the matched S-525 ($370) center requires a 4ohm friendly receiver. I've owned all of the above (except the S-525) and all are excellent for the money.
If you're in the US you can often find Onkyo's TX-SR608 brand new for around $400 shipped. It's a good little receiver but isn't 4ohm friendly. If you don't need 3D compatibility then last year's 4ohm friendly TX-SR707 can bought (factory refurb) for
$400 or the 3D capable TX-NR708 (factory refurbished) for
$520. To me the 70x series are worth the extra money. FWIW I've bought factory refurbished receivers from them twice with zero issues.