First and most importantly
Room to swing freely to encourage letting go
Fairway and greenside bunkers used sparingly but occasionally with enough bite to teach strategy and recovery technique
Closely mown areas around the greens to allow runups and teach chipping, but occasionally some rough around greens to practice recovery and provide variety.
Reasonably undulating greens.
err on the shorter side overall, but with at least a couple long 4's a 5 and a 3, so all playing levels could be taught.
a variety of undulations on the fairways on at least a few holes.
at least a couple of holes preferably well and somewhat tightly defined by trees(or well defined bunkers) to teach and quantify driving skills for better players, but with minimal undergrowth to allow lesser players to stay in the game, preferably with the more forward tees not quite as pinched by trees.
So overall the course would be on the easier/fun side, but there would be areas where the elite players could practice as challenging of a shot as they wanted, but also other areas where the newer players could develop confidence.---preferably in various three hole loops.
Locate the range and learning center in the middle of the course where players could set out in small loops, with the ability to connect and play up to 9 or 18 holes
more as it comes to me
the three(ish) hole loops would be arranged where maybe for newer players holes #1,2,3 are fairly wide open, shortish and subtle and very sparingly bunkered, but maybe a few fairway undulations thrown in for sidehill lie practice.
Perhaps another loop for better players has the aforementioned tree defined driving corridor/drill area, another hole with a steep bunker or two, and maybe some relatively deep rough to practice recovery and distance control from flier lie situations-
Maybe even some of my pet peeve dreaded "native" well wide of normal play on a wide hole, ON ONE SIDE to provide texture, provide practice from taller grass, and give a better player the ability to perhaps try to hit an imagined target/preferred area nearer to it.
another loop may have a mix of ability levels.
No tee markers or tees-gang mowed areas where the players tee off where they want-some level-some not
a few functional,even pedestrian holes where confidence can be gained, but several really memorable and or particularly scenic holes that make practical use of whatever landforms/attractive features that are on the property.
During Jr. clinics/camps, parents could play 3-6 hole loops while in proximity to their kids, then join them for more golf of picnic afterward.9see below)
make the range/practice area a friendly and relaxed area, where newer players are welcome and encouraged,with picnic benches and shade trees, water fountains, and maybe even barbecue pits
(OK visions of Happy Gilmore's happy place did come to mind
, but we'll keep this G rated......)
Have pros/good local players/high school kids working on greeting and encouraging people-which will no doubt pay huge benefits for them as well as the facility owners.
On the range lots of short targets 20-100 yards out cut at fairway height for definition and so ballmarks aren't a problem-fun things like a free pizza/pitcher of beer for hitting a ball in the bucket.
Music playing, but not blaring.
an interesting, fun putting green with more than 5 pins
located at random distances, not the stock 20 feet apart
.
Practice bunkers where a player can hit to short and long targets on the range, and if they skull it they don't kill anyone.
mats OK, but not the generic square ones, but rather the nice, quality,free form ones available and used so that a variety of shots can be practiced even when poor weather/turf make grass impractical to use. Most importantly, seamlessly slipped in amongst grass areas so being on the mats is a pleasureably thing working on the same shots as the grassed areas, not stuck in a corner hitting the same shot off a big rubber tee
as Peter says, make it a place a beginner WANTS to come back to, but also a course that has enough interest that a good player stays interested. Aiken Golf club comes to mind as far as course size, Palmetto's 3 hole upper loop near the clubhouse is perfect for players of all abilities.