Lots of good questions guys and after a decade of experiments I've learned many lessons about vegetable gardening and fruit tree growing.
I did start out growing most of my crops in furrows and this took a great amount of digging by hand. Than I upgraded to using a beast of a tiller to work the ground over each season like a mini farm but honestly I haven't dragged that machine out for ages.
Raised beds are where I have evolved to now days and the main reason for this is because it's easier and if you are doing a lot of work on your property like me then savings in physical energy and time becomes valuable indeed.
And, the higher raised beds (around 70 - 85 cms) are my favorite. After a day in the garden, my back and knees really appreciate stand up gardening it makes a huge difference especially as you get older or suffer from injury/disability.
I still have a mix of lower raised beds and higher raised beds with a small "wild" area at the back of my patch for odd plants not suited to raised beds such as rosella plants as they get too big.
However, if I started over from scratch I would buy or build all high raised beds, actually I probably wouldn't even bother using wood sleepers I would simply use galvanised or colorbond raised beds - they last longer and are easier to build.
I'd get several different shapes because round, rectangle, oval, or hexagonal can be useful for different crops but they'd all be 70-85 cm high - except for my "wild" area where I'd either keep in ground or small raised beds no higher than 40 cm to grow higher plants like corn or rosella (as I mentioned earlier).
Tomatoes come to mind also as a tall crop requiring a small sided raised garden bed, although, I'm working on ways to grow them in high beds and I've had recent success tumbling indeterminate tomatoes down over high round beds (no stakes)
Crops that historically have been grown up like beans or peas for example can be trained to tumble down or climb over an archway in between two raised beds. I'm trying all these things and I reckon it'll work but if it doesn't I'll always keep a few raised beds with smaller sides for these types of plants.
There's other good reasons for high raised vegetable garden beds besides being easier to dig, weed, harvest, or irrigate, such as: less pests/animals, better soil development over time, easier crop organisation, and they look good.
I'm currently writing an article about raised beds covering the points above in more depth and I'm also chatting on Sunshine Coast radio this Monday about this very subject so hopefully I can post a podcast of our conversation here and a link to the article when it's done.
The other major thing I would change if starting from scratch is to ensure the access areas and pathways around my vegetable garden beds were well drained particularly in a high rainfall climate because these areas quickly turn to mud in a well used veggie patch during bad weather. I've fixed this problem now but I did take the long road in doing so.
Also, I wished I had built my initial raised beds so I could reach the centre from the side without getting into the bed. Walking into the garden bed to dig, weed, harvest etc is not only inconvenient or difficult when the bed is full of plants but it also compacts the soil which isn't good for food crops.
I make sure the centre of all beds I build now can be reached without getting into it.
Our patch is about 16 x 40 mtrs. Our composting area is at the back of our vegetable garden it's handy to have it close by and it should be big enough to hold several heaps of compost on the go, a pile of ready made compost, plus the odd dump of manure maturing before being ready to use. Of course, your composting area is relative in size to your garden so for ours we have 3 large bays.
One thing I did get right from the beginning was the positioning of our vegetable garden. Full sun most of the day and away from large trees shade and roots.
Food gardening is high energy stuff and full sun is very important when it comes to growing productive and healthy plants.
Having the patch positioned central in the backyard overall is handy for access and it's practical. Some people want a vegetable garden but don't want it to be seen - this can be a mistake... we use our patch as a showcase so we deliberately framed it right in the middle of our back lawn.
This also had an unintended advantage in regards to damage from animals like possums. Due to the several metres of grass between our patch and the nearest tree there's much less crop damage.
In the beginning, I did place a few beds closer to the trees and unless I netted them the crops would get smashed but since moving all the beds to the central location I hardly ever see any crop damage from animals.
I'll have a break from typing on my phone and write some more in another post soon including orchard or fruit tree sighting and what worked for us.