My audio experience is primarily in the world of public address rather than home theatre, but there are a couple of things to consider when putting together any system, whether it be PA or HT.
(assuming we're talking about your standard bread & butter multi-speaker HT system and not talking about tricky things like sound projection systems etc)
Rather than suggest systems or brands to look at, here's some general tips to help you understand about picking a system. General things so you know what you're looking at and how to use it effectively - things like speaker placement, system tuning and room dynamics. They're worth more than you can imagine and fiddling with these things can often be... well... free Speaker placement
In the simplest terms, the little speakers should be at around ear height and the big speakers can be (almost) anywhere. Treble is very directional and doesn't travel through objects while bass is relatively non-directional and can travel through objects.
Most of the sound that matters comes out of the front (centre for most voices when watching a surround source and FL/FR speakers for a stereo source), so getting these positioned at the right height place is pretty important. Consider if you get discrete components, with BIG speakers, you'll need BIG speaker stands which take up lots of real estate and cost a lot. They're also.... ugly (says me who works with PA speakers).
Since lots of HT is about BIG BOOMS and BANGS, people like having LOTS OF SUBWOOFERS MOITE. Unless your room is huge, one sub will probably do and I reckon an 8" or 10" speaker is about right. Bigger subs will hit super low notes better, however tend to flex and not respond to a second hit as quickly. Smaller ones might not be punchy enough.
Remember that corners accentuate bass. Try it for yourself if you like - play some music and go stand in the corner. As you walk towards and away from the corner, notice how the bottom end of the sound changes. Putting a sub out of the way in the corner can lead to weird low end sounds sometimes.
Some speakers have ports (holes in the side with no speaker). Don't block them up with a wall or bookshelf because they're there for speaker tuning. Some "bookshelf" speakers come with rear ports which is really confusing if you ask me. If say your sub has a rear port, you'll need some clearance from the wall for it. System tuning
Actually having someone to fiddle with all of the knobs to get the balance just right can be pretty handy. Can't say much about this without getting too technical. The main thing I'll say is don't overdo the rear fill. Lots of people crank their rear speakers up cos they want to get "lots of surround sound". Honestly, it's just a novelty factor and they're just there for fill. If you have too much of it, it's really distracting and can overpower the really important stuff that's happening in the front speakers.
Some (not sure how common this is?) package systems come with a auto-tune option, which is basically a mic which you place at the listening position and the system tunes itself based on that. Most usually work okay, so it might be a consideration if you don't want to fiddle too much. Room dynamics
All surfaces have different dynamics, as does the absence of surface. Hard surfaces such as floorboards can reflect sound a lot, while soft surfaces can absorb sound. The differences between surfaces can impact how you might want to place your system. A window (hard) on your left wall versus a large tapestry (soft) on the right wall can unbalance your sound. Also, if you have a big open archway putting that on one side can also unbalance things, while putting behind you is probably better on the balance side of things.
The optimal listening position isn't actually dead centre. since you can get funky things going with sound from two speakers cancelling itself out. Just left or right of dead centre is probably the best, where the differences between speakers isn't noticable and you're less likely to get any cancelling going. System choice Very subjective stuff coming
I reckon 5.1 systems offer the right balance. They're very practical and offer enough surround sound for me. Applying all of the considerations above, can you REALLY be bothered with 7.1 or 7.2 speakers? I reckon the benefit vs cost (which includes, monetary, setup hassle, real estate, ugly) of some of these mega HT systems is heavily weighted towards cost. Are the extra speakers there to show off or do they REALLY add THAT MUCH to your cinema experience? And do you even watch that many shows which will make full use of it?
Package systems generally work pretty well if you don't want to think too hard, since most of the speakers will have been designed to work well with each other.And in closing
Sound is really subjective and lots of what I've said is opinion based.... let's see what pure-HT buffs like Blybo have to say