Some guidance please?

1-your amp will make a world of difference
2-don't skimp on the sub. A good sub will handle the bass tracks plus the low bass for all 5/7 speakers.
3-Decide on where you need the speakers-wall mount, stand mount, bookshelf, near walls, (most sound best away from walls, what size is your room......
4-used is usually great as long as you don't mind used. New depriciate 50% right out of the box. Polk depriciate more than that.
5-I love my set-up, which you could easily afford: 5 soliloquy sat-5's (new $400 each, used or B-stock $200 each), velodyne uld 15 sub(new $1995, used $400). $1400 for a $3000 set-up works for me and is probably pretty standard to what you can find out there.
Try:
jeffssoundvalues.com
tsto.com
hififarm.com
jmsound.com
hcmaudio.com
echohifi.com
audioadvisor.com
upscaleaudio.com
many more too.......

Don't buy speakers at all. They just clutter up your listening room and cause you to buy all that expensive speaker wire from the wire bandits. Little kids always push in the tweeters and the cat is attracted to the grills. Skip the speakers altogether and spend the money you are saving on a better receiver.

Viridian, you seem like quite the witty character. I was about to dismiss your advice until I read some of your feedback. You're obviously a knowledgeable audio enthusiast(and a bit of a comedian). I always thought Denon made very good receivers. Why do you think differently? Any speaker would be completely safe in my house. I prefer dogs to cats and at 31, I know better than to push the tweeters in.(my girlfriend keeps asking me if I'm ever going to grow up!)

Guilty on all counts! I would caution you that there is quite a bit of folderol on this site, though it must be less than on some others. If you doubt this check the chat section and click on "disputes". Audiogon stopped airing these openly about a year ago, but you will get the idea. Many center around the misgrading of gear but there are a lot of diputes regarding shipping damage as well. Which brings me to my next point. After turntables, speakers are the most likely items IMHO to suffer shipping damage. Go into shipping speakers eyes wide open, and deal with someone who is very familiar with shipping speakers. Double boxing can be a not inexpensive, but valuble option that I ususally require.

That said, there are many good speakers out there. Modern computer analysis and modeling has become a valuble tool that has really helped modern designers to deliver an incredible product at very modest prices. The best advice is to get out and listen to find out what your taste is. That said, I like the speakers designed in Canada with the help of the NRC; any time a government wants to pay for loudspeaker research that works just fine for me. The Paradigm and PSB brands are just great. Easy for your Denon to drive with robust sound, they make a lot of nice models to choose from as well. They tend to be well regarded and plentiful on the used market. Check out their websites. The Denon is a marvelous receiver; I was just being crass, as ususal. Viva la cats.
Marty

As usual you're getting some good advice here. I second the Canadian speaker recommendation. PSB, Paradigm, Pinnacle (I don't know why they all start with P - it's a Canadian thing eh?) - all excellent values that you can drive easily with the receiver you have.
Now - Size - yes size matters, but in different ways than you might think (ask your girlfriend and push in her tweeters while you're at it) No you're not ever going to grow up - get over it already.
Large speakers usually mean better bass, while smaller, stand mounted speakers usually have better imaging. You already have a sub, so maybe smaller speakers (called monitors) could be your thing. They take up less floor space, are less obtrusive looking and often are better for music.
PSB used to have the Stratus Mini, which was superb - you could get two of those, a C6i center and some Alpha's for the rear and be way under $2k, and have a great sounding system to boot. Oh, and they're easier to ship. 100lbs of speaker costs a fair sum to ship.
Put some $ into decent cable, and you're ready to go.
have to agree about Polks - not a bad speaker but sinks about as fast as Big Pussy on the Sopranos price wise - as does Definitive Technology, which might be something to consider for a real theater speaker - flabby uncontrolled self powered built-in subs - dreadful for music, but fine for your next blow-em-up action film.