Andrew,
The N3 makes a great speaker for both HT and music, I have a pair in my living room with upgraded crossovers (Sonicaps, Mills resistors and Platinum by-pass caps). Unfortunately, the Neo3 PDR tweeter is no longer available. Sometimes you can find these tweeters for sale on E-bay. If you can get three of them you could get the rest of the kits for a pair of N3's and an N3S center channel from Danny.
Another really good option I have built for others is the X-MTM Encore. These are X-CS Encores in larger floor standing cabinets which are -3dB at 40Hz. So three X-CS Encore kits would give you a pair of X-MTM Encore towers and an X-CS Encore center channel. You could also build them as three X-CS Encores and place two on speaker stands. Obviously they wont have the low end extension of the towers but you could build subs into the stands such as Danny's "Best Speaker Stands Ever"
http://www.audiocircle.com/index.php?topic=129161.0 . With this combination you would end up with a pair of full range main speakers.
The X-series speakers come with a stock PCB crossover on which you can upgrade the capacitors and resistors. You can also point-to-point wire the crossover network the same as you would with the N3's. This is what I did for the X-MTM Encores I built. While the stock Encores are very good speakers and for the price I doubt they could be beat, the upgraded Encores are truly exceptional.
If you want to stick with a smaller speaker for the mains I would recommend the X-LS Encore over the X-LS Classic. Again, the same comments about upgrading the crossovers apply to the X-LS as to the X-CS (or MTM) Encores. If you want to go this route you might want to check these out:
http://www.audiocircle.com/index.php?topic=138999.0 .
Either way you will need a sub for HT. My preference is Danny's direct servo subs. I have a sealed 12" servo sub paired with the N3's in a 20' x 25' x 8' living room. Shakes the couch and walls when something blows up but you can actually understand the dialogue that comes after the boom. Also, the best sealed sub for music I have ever heard.
If you have the space to pull the speakers at least 3ft into the room you should consider Danny's open baffle models. I have a pair of the Wedgies (
http://www.audiocircle.com/index.php?topic=126112.0 ) upstairs and these things are so clean, clear and image so well I don't need a center channel speaker for HT. The Wedgies only play down to 200Hz so they absolutely must be paired with a sub for each channel that can play up to 200Hz. Since the Wedgies are open baffle you really want open baffle subs to blend properly. The Wedgies use the Neo3 PDR tweeter and have a waveguide built into the front baffle so availability is very limited. I have enough drivers and cabinet material to build three pairs but that's all.
Danny is working on three new open baffle speakers, two of which, the NX-Otica and NX-Tream are also going to have limited availability because they use a special modified version of the Neo3 PDR and Danny only has a few of them. Here's a link to the discussion of them
http://www.audiocircle.com/index.php?topic=138009.0 The third version, the X-Otica, uses the the same Peerless tweeter that's in the Encores so there won't be an availability problem with these.
http://www.audiocircle.com/index.php?topic=138007.0I hope this doesn't qualify as information overload
Mike