I am currently playing DYO with Mike the Younger and Jack Dionne from the WASLC. We have been meeting semi regularly to tackle every theatre of WWII in med-sized , point-wise, DYO matches. The further we got into it the better we have become at organizing and setting up DYO, it's all a matter of practice.
We have listed all the various actions we want to play out. So far Mike and I have done a Barbarossa, France '40 and a desert DYO. With Jack I played out a Kahlkin Gol and a Early '45 U.S./Ger DYO. Point totals are usually under 3000 and are in a 3/2 ratio with 1.2 RF with the option to buy .1 increases in RF as per Chapt. H
Boards and overlays we choose on the basis of research, Google Earth is your friend here, with various on-line resources such as the excellent Combined Arms Research Library, and letting the creative juices flow. For instance for the desert scenario we toured Libya with Google Earth and that made the orientation of Wadi's and Dunes accurate for our chosen terrain. We use as many boards as my 4 x 6 ft table will hold and go nuts with the overlays finally covering it all with plexiglas.
There is a DYO program Jack Dionne found for me called ASL DYO Assistant 3.0
It's available for DL IIRC. VASL can also be helpful for the defender to print out all the HIP units and fortifications.
VC's are the most difficult and the easiest. Slugfests are fine, those are easy. The more complex ones ie. exit VPs, terrain objectives, CVP caps etc are more difficult to work out, but if you arrange it so each side has conflicting objectives such that they are bound to bring each force into contact it is not too difficult to ensure a satisfactory battle.
Advantages:
Fog of War. Points, rarity factor and scenario date will allow some insight into your opponents OB but you will not know exactly what he has until it is in LOS. I love this.
Open flanks. With large board areas and relatively small forces, flank protection becomes much more important. Board edge creepers still occur from time to time but are not as prevalent as regular scenarios.
One DYO, many scenarios. Mike and I saw this in our France 1940 scenario. We had six small scenarios within our DYO. Hill battles, breakthroughs, counter-attacks, Tank vs Inf fights, a river crossing, all going on at the same time with long range ATG and MTR fire over all the map not to mention the OBA's. It was great!
Disadvantages:
Balance. I don't think this can ever be counted on. It can be achieved but not assured despite your best intentions and efforts. C'est La Guerre.
Ties up your game space and takes a long time to play. I have the luxury of a dedicated space to let the game stay set up. You may not be so fortunate. Overlays take a beating too if your sticky stuff stays on too long as well.
We have had a blast playing DYO