This web page lists techniques for making your garden "deer resistant":
- Plants they don't like
- Deer repellent
- Deer fence [your wife won't like these, they have to be 8 feet tall to keep deer out]
- Motion activated sprinklers, lights, noise makers
- Pie pan noise makers [the aesthetics of this may be questionable to your wife too]
You mention other critters, but don't say what kind -- rabbits, woodchucks, voles? The control method will vary greatly:
- For rabbits and woodchucks:
- a low fence might work, but you'll have to bury part of it since they can dig
- more smelly sprays
- traps -- live or dead
- For voles, good luck... maybe an outdoor cat or two?
- Some of the motion activated noise/light devices may work well on other animals depending on what is invading your garden.
- Raccoons can be deterred with a couple of low strands of electric fencing around the garden. I don't know if this will count against your fence ban -- it's a temporary fence that could be taken down after the growing season.
Fences are the most common advice I've seen (and what I use) and from what I can tell the most effective. If you can't do this, you may want to try some of the sprays/repellents. E.g. fox or cat urine.
Depending on the animal, some people use a live trap and then transport the animal far enough away to make it someone else's problem. Just make sure you can deal with a live trap in a timely manner -- leaving an animal die slowly baking in the sun all day is much worse than just using an "instant-kill" trap.
Again depending on the animal, you can cage the plants, e.g. small cubes of wire fencing around your spinach, lettuce, etc to keep small animals off.