Help with getting best sound from room

I am in the process of upgrading our 2 channel system and would like some ideas on getting the best sound given the constraints of the room.

The room is 18 feet long x 12.5 feet wide. We sit along the 18 ft wall and have the speakers directly across from us about 10 feet away. The speakers are bookshelf types on stands and are about 8 ft apart and are out about 2 feet from the back wall which is mostly window. The ceiling ht is 8.5 feet and the walls are basic drywall material. Listening is mostly at moderate levels and consists mainly of rock, jazz, blues with some classical. Our current setup uses a Squeezebox as source playing FLAC files and a Cambridge Audio 540Av2 integrated (just purchased on this site), and older Altec 101 bookshelf speakers.

Overall we are happy with the sound but I am wondering if there are some basic adjustments that can be done to improve the sound of the room in general. Secondarily, can some input be given on the type/brand of speaker that might be a good match to the room. Budget would be <$750 for the pair.