This was a mistake.
We discovered the most obvious damage after returning from a week's vacation in June to find that all the tomatoes in our annual beds had been pruned down to within a foot of the ground. We even found a sunflower with a big deer-shaped bite out of it (see photo here).
The less obvious damage was even worse: the deer were pruning all the fresh growth off of the dozen fruit trees we'd planted, and trampling the asparagus bed. The chickens were doing their part too, by removing all the mulch from the asparagus and exposing bare soil.
To combat the obvious damage, we installed 5' steel t-posts around the annual beds and wrapped it with black plastic net fencing. This deterred the deer and chickens from getting into the annual beds, which was nice, but we really should have fenced off the fruit trees and asparagus too.
Also 5' t-posts are too short to be very effective. The first 1' goes into the ground, leaving you with 4' above ground, which, to a deer, is about as challenging to jump as stepping over a 36" wide raised bed is for you or me. If they have other things to eat in the area, and the ground inside the fenced area is uneven, then it will deter them, but if they really want to get in it won't stop them. I now prefer 8' t-posts, which leave 7' sticking out of the ground, and are about as high as I can reach with the post-slammer without using a ladder (I'm 5'10").
Since the fencing we had was 7' wide, we tried fastening bamboo extensions to the posts to make the fence taller, but they kept falling over. I'd definitely recommend longer posts.
We got 8' t-posts and fenced in the entire front yard (including the lower two swales and the hole-in-the-ground-that-will-someday-be-a-pond), not just the annual beds. We used 16' cattle panels for the lower 4' and two strings of galvanized 14ga steel wire for a total height of 7' - then we wrapped the bottom 2' with chicken wire to keep our birds out. While this certainly wouldn't be tall enough to keep deer trapped inside, it seems to be effective in keeping them out.
We also sunk 4x4 pressure treated posts into concrete and installed 2 fence gates. Our gates came with chain-style latches that wrap around the post and lock into a notch back in the gate, but they're annoying to use one-handed if you're carrying something (which I usually am), so I want to upgrade them to gate fork latches, which should be easier to use one-handed.
A note on concrete for fence posts: after trying a few methods, I like to dig the hole, set the post, pour dry concrete mix directly into the hole, sprinkle water on top, and re-check the post with a level. It's less work than mixing the concrete with water in a bucket, and you're less likely to add too much water and weaken the concrete.
We moved the black plastic fencing to the long swale and protected the whole thing from deer and chickens. Here you can see two of our fruit trees (a plum and a cherry I think) that are smaller than they should be after losing most of their first year's growth to the deer.
In hindsight:We would have spent the time and money to fence in everything the first year (especially once we realized how much deer-pressure we had). It doesn't make sense to spend money on 1-2 year old fruit trees and then fail to spend money protecting them.
I'm not sure if the plastic fencing or the steel fencing is a better deal. The plastic claims it's UV protected and will last for years instead of rusting, but our galvanized steel fencing still looks great a year after installation. The steel is more modular, so we can easily remove a panel to get a vehicle in to drop off straw or compost. We took down the plastic fence last winter and put it up again in the spring (the theory being that snow loads would shred it to pieces if we left it up), which made it much more labor-intensive than a metal fence that doesn't need maintenance. This coming winter we're taking the Darwin approach to fencing: if the plastic fence ($0.61 per linear foot) dies, we'll replace it with metal ($2.00 per foot), but if it doesn't, we'll leave it.
If we do go with metal for the next round of fencing, we'll use 'variegated height hog panels' instead of cattle panels. While they're shorter at 34" instead of 48" (which means we'll need a 3rd string of wire above them, the wires are close enough together near the ground to keep chickens from jumping through them.
Lastly, before putting up any fence, I'd ask what animals it needs to stop. We care about keeping deer and chickens out - if we want to eventually get pigs, the plastic fencing will be useless, and the steel fencing will need reinforcements (i.e. more t-posts spaced 5-8' apart, not just 16' apart). Foxes, bob-cats, and other predators will be able to climb the steel to get to our chickens, but probably not the plastic. We have zero protection right now against things that dig under fences (because it's a heck of a lot of work).