I am a Sonos dealer and installer. The plan to hard-wire is a good one, but if you're putting in the Cat6 just for Sonos then it's overkill: Use Cat5e instead. That might seem a backwards step given that everything is going to faster cable in home installation, however, the network traffic for Sonos isn't anything like as heavy as moving the data bits for video streaming. Cat5e will handle Gigabit speeds up to 100m, so unless the house you're wiring is some sprawling mansion then Cat5e will be more than adequate for audio streaming even of FLAC audio files.
For wireless operation Sonos runs on the 802.11b wireless standard. The benefit of 'b' over g and n is range. The downside is it's more prone to interference from lots of other stuff that inhabits the same frequency spectrum. e.g. wireless video senders, baby monitors, microwave ovens, etc. I've rarely found it to be a problem though because the Sonos speakers and streamers do buffer quite a bit of data so they're pretty tolerant. Situations can change and not every install is the same (quite obviously) so I'd still favour wired over wireless where practical, but the advantage of running wired is as much for the benefit of other devices on your network.
If you're going to the trouble of running cable for the Sonos gear then have a think about running Cat6 for any device that will be making use of video streaming (e.g. TVs, media players, games consoles) and for any storage devices such as NAS drives, PCs and the like. Getting them off the wireless network will free up bandwidth for other dives that don't have a wired option (e.g. tablets, smart phones).
You're planning to put a Playbar in the lounge with a pair of Play 1s for rears. That plus the Flexson brackets will set you back around £1100, and that's before you shell out another £550 for the sub which would make the grand total over £1600. I know what you're thinking: "I won't need the sub just for telly" and you're probably right. The point is that for very similar money (around £1100) you can get a better sounding and far better specified lounge surround system and still have all the benefits of Sonos too. This is one of those rare times when you can have your cake and eat it as well.
Don't get me wrong, I love Sonos. It's the best of any of the wired and wireless whole house audio systems up to the point where you're paying new car money for Linn or Naim. Playbar isn't a bad product either. In fact if all you want is some better sound from the telly that also incorporates the Sonos features and money isn't up there in your top three concerns then a Playbar ticks a lot of boxes. However, if a customer asks me "Is this the best sound I cam buy for my money?" then the answer is 'No'. Once you dip your toe in that pricey pond and do a little digging then you start to uncover some shortcomings. These may or may not bother you, but wouldn't you at least want to know beforehand so you can make the best decision you can rather than finding out after you've splashed the cash?
Playbar's appeal is it's simplicity - you connect it to your TV via an optical cable, and that's pretty much it for any sort of AV connections. The TV acts as the hub for AV switching. This means your Sky/Virgin/BT/Freeview/Freesat recorder plugs in to the TV as do any other devices. As you change HDMI input on the TV the Playbar gets the corresponding sound. Its the same with any Smart TV streaming too; the Playbar lets you hear that as well. So far so good....... Except no-one (until now) makes it clear what the TV does to the sound it passes to the Playbar. Read on....
You're spending £300 on rear surround speakers plus another £50 on Flexson brackets for them, when from a TV recorder (Sky Virgin etc) and Blu-rays and games consoles the best sound you're going to get will be ProLogic. That's the one with the kind of fuzzy indistinct rear surround because a lot of the time it's fudged up from a stereo audio source. That's not the Sonos' fault. It's simply dealing with what it is given. The issue is the TV. The vast majority convert whatever sound format they receive via HDMI in to simple stereo. In the process they throw away all the dedicated surround audio information that's encoded in to films and TV programmes! Things improve slightly with the TV's own tuner - at least with that you get Dolby Digital for the odd HD channel that carries a fully encoded programme, and the version of Dolby Surround for most channels does include some rudimentary rear channel encoding so it'll sound a bit better than plain stereo mocked up in to surround. Its a similar story with streaming: If using the TVs own Smart functions then you'll get Dolby Digital sent to the Playbar.
Playbars have an upper limit to their sound performance. The best they can handle is Dolby Digital from the Optical input. That's a moot point if it is only ever going to be connected to a TV as I have discussed above; but if you're a film fan or console user then you'll miss out on the better quality sound tracks available in DTS, Dolby TrueHD and DTS Master Audio.
So what are the alternatives?..........
The obvious is one of those all-in-one surround systems with a built-in DVD/Blu-ray player such as Currys/PC World sells. Quite honestly, I'd rather stick needles in my eyes before recommending anyone to waste cash on on those, so let's move on to the proper stuff.
A real surround system is made up from an AV receiver which handles all the signal processing and switching and amplification. That's then connected to a set of speakers, and in most cases this is five smaller satellite speakers plus a bass speaker. We call this type of speaker kit a sub-sat system. The advantages of a proper surround system are that it sounds better (and by a substantial margin) than an equivalently-priced all-in-one; it has more inputs and no practical limitations on what can be connected because the system can cope with all the current audio formats.
Here's what I'd recommend as an alternative kit selection
Electronics:
Yamaha RXV479 AV receiver -------------------------------------------------- £269
(or Marantz NR1506 slimline AV receiver (if space is an issue) --------------- £279)
Speakers:
Monitor Audio MASS 5.1 speaker system (1x centre, 4x surround, 1x sub,) - £599
Full Sonos functionality:
Sonos Connect streaming player ---------------------------------------------- £265
Total--------------------------------------------------------------------------- £1133