Start with a good site survey to determine your needs from the prospective of signal strength & quality, decide on how you are going to authenticate and authorize the users, decide where you'll need redundancy, and decide how you'll monitor & manage.
Since you posted here, you're looking at Cisco, and that's a good thing. They have a pretty good suite of hardware and software (as well as support and maintenance plans).
Chances are you'll end up with a "Lightweight" AP setup (LWAP), where all of the RF heads will connect back to a wireless controller.
LWAP makes it a bit easier to maintain and manage.
Now that you can get the "old" (formerly) stand-alone Aironet APs with LWAP firmware, you also get to keep some antenna options for special circumstances.
It would be helpful if you could provide some additional detail regarding the topology of the area you need to cover (high-rise / spread out, distances, construction materials, etc) ... no one here can give you a definite bill-of-materials (and if they do, ignore it) ... but given a certain layout, some recommendations are "cookie-cutter" easy.
To go back to the opening line; make no firm decisions until you have a solid, comprehensive site survey. If you haven't ever done one, then hire someone that has ... and has the equipment and track record to prove it.
Once you have defined the goals (SS, SQ, auth, auth, management, maintenance ... )then have the site survey to define the coverage needs, you can start selecting equipment and try to fit the budget.
Other tings frequently overlooked:
* Cabling cost (the APs have to connect to a wired infrastructure)
* Equipment physical security (this stuff should be behind locked doors
*Environmental conditioning (Air, power / UPS, space)
*Troubleshooting
*Maintenance (firmware updates, HW replacement)
* Redundancy / replacement / hot-swap
* Servers for things like RADIUS, ftp/tftp, drivers, consumer utilities, user management
* Other security (firewalls) & remote access
...and again, doing / getting an air-tight site survey will eliminate nearly all of the post-install problems related to coverage, throughput, and quality user experience.
Putting it together is easy .... connect a bunch of dots ... making it work well and stay reliable is the big trick.
As far as documentation goes, Cisco's main site has some prety good planning docs.
I'm sure Rob H will have some pretty good pointers too; watch for his posts and do what he says (edit: and, of course, he beat me to the post ... ;-})
Good Luck
Scott
