I've been building and installing gates (and other ornamental iron) for a living since '99. (learned to weld in '79) (And Paul at Zero Tolerance can still woop my a** when it comes to sweet lookin' beads!


)
Some things to consider before you make any in depth plans:
Check with your local zoning board, some (but by
no means all) will require fees and design considerations.
Check with your local fire Marshall, some will have guidelines they want met to insure their access in case of emergency.
Check with your local building and inspections office, some will require permits and may have codes you'll need to adhere to.
If you live in a sub-division with its own by laws you may have to deal with that **** too.
There are many many locales where none of this applies, but it's worth finding out to save you from future headaches. This stuff doesn't always get enforced but when it does re-do's aren't any cheaper than the first go 'round and in many cases can cost more.
I read in a trade rag recently that
UL 325 safety standards are going to get written into IBC2012 which is the code model for most of the USA so you'll probably begin to see more hoops to jump through for gate installs in the future.
I also read where NHTSA has wrote a new regulation to the effect that you'll have to have a wide reflective conspicuity stripe across any gate that leads to a public roadway, including residential gates.
More nanny state **** to save us from ourselves if you ask me. I don't see that as a complimentary effect on a nice hand wrought gate.
Several industry groups are gearing up for a fight to see if they can stop the madness before any state DOT's adopt and enforce the rules.
As far as the gates themselves go here's a few tips I've learned over the years:
The hinge post needs some serious beef depending on the size and weight of your gates. For something in the 300-500 lb and 12' to 16' range I'd use a post with a 6" profile and 1/4" wall as a minimum.
For a super duty gate post dig a trench across the drive way drop a beam in it and weld both posts to the beam.
I'd also set it in nearly a yard of 3000 psi concrete and the fiber is a great addition. I usually go with 4000 psi w/fiber on something that big. More often than not I'll dig a 30" by 30" by 30" hole (3/4 yard). But you may want to go deeper in colder climates to stay below the frost line.
Nothing wrong with a little re-bar in the footer either, but don't loose any sleep over it if you don't use it, especially on the smaller footers like the 3/4 yard cubes.
For lighter stuff you can set them like any farmer would. Bore a hole (I like to go 1.5 times whatever the above grade height) throw in some gravel and the post then plumb it, throw some ready mix (Red bag) and water at it and go eat a sammich while it cures, then hang the gate.
If you plan on operators do NOT cheap out on them. (One word: get Door King

) You want these things to last for ever and good electronics and installs are not even close to cheap. Generally the more you pay up front the less you'll pay down the road. And they all break eventually.
(I used to sell turn keys gate installs w/access controls myself but finally quit selling the electronics, too many chances for warranty work. Now I just team up with an access control outfit and let them handle the sparky/digital/telephony stuff.)
If you live on a mountain top do some serious ground and lightning protection. It will get struck and when it does it'll eat a board up in the control panel, so get something with a proven parts/service history.
If you're going to use operators one piece swing gates are cheaper than dual. If you have the room good sliding gate operators seem to be more durable than swings arms or linear swing gate operators.
If security is an issue sliding gates generally are harder to defeat than swing gates. A set of stout bollards at each end and a serious slide gate can stop a small car easily. It'll have to be fixed but if it stopped the crackhead in the F onefiddy from hookin' up and taking off with your Fountain (I'm more of a Chris Craft guy) it was money well spent.
If your not going to use an operator you might want to add a second latch post to lock open as well as closed.
If you want the cheapest steel gate you can find get a couple of Locust posts and one of the thin wall specials from places like TSC, that's about as cheap as you can get, aside from just stringing up a chain.
Use good sealed bearing or barrel style w/grease-able ball bearing hinges.
If you're going to make it yourself blast and powder coat it and it'll last for ever.
Drill small weep holes on the bottom of any tubing to keep it from freezing and splitting in the future.
I've got lots more but I believe I've

enough for one post.
Hope this helps.
Havefunbecarefuldrivesafe, ya hear?