Hello all, just noticed this thread.
No one has suggested a rock rake on a tractor. If your main goal is to get most of the gravel out of the yard, that would save a lot of back work getting it all to one side or in a pile, IF it's not compacted to badly. You may need to scratch if first with an all-purpose plow. Maybe you could find someone who could use it as a base layer to haul it off, maybe free, or someone could use it who has a gravel driveway in the country where appearance might not be too critical but they want to fill in some ruts. The small tractor you have available would probably load a pickup.
What's that saying about every man's trash...?
Considering the above compaction question, it is possible that simply covering what you have with soil would create a hardpan that would prevent adequate drainage. That may have already been addressed and I missed it. If so, I apologize. I have seen that happen more than once on old store sites, road banks, etc where 90% had to be replanted because they were sitting in a water table 6-8 inches below the surface. May not be a problem with your site, just something to consider. Dig a hole like you are doing a perc test and see what it does down in there, at least ballpark.
Since you plan on selling, at least a decent lawn would be good for the curb appeal, but I like the idea of shrubs and flowers. Don't know how long that fence area is but you could do a lots there with some mixed evergreens- boring azaleas, hollies, etc. Well, the azaleas are boring if everyone else on the street has them, but you could use them as fillers with a few more expensive shrubs, couple of Knockout roses. Oops, there I go designing and we're supposed to be getting rid of that gravel!