I've lived in concord around 5 years. Mom has property in Pleasant Hill for far longer than that, i lived in PH for 2 years.
PH is part of the Mt. Diablo School district - which is to avoided at all costs. the middle school in PH is pretty good, but almost all high schools in this are not good. problem is, while the PH kids might be good, Mt. Diablo School district is HUGE, and they take their *worst* preforming kids from their worst schools, and bus them into PH for a "change in enviornment". you can take the kid out of the ghetto, but rarely can u take the ghetto out of the kid. so the schools anywhere in Mt. Diablo arnt really so hot. Martinez is MUCH better, and smaller - which is a good thing. If you can afford the cheapest shack in Lafayette or Orinda - DO IT. those are high income level cities, with their own school district = good schools.
I think real estate in PH and concord is still going up, not as fast as it did in the last couple years, of course time will tell. but i think the housing prices around here arnt going to drastically drop anytime soon. people are getting priced out of the east bay, and are discovering concord really isnt that far from "the action" of the bay area. no one wants to be as far out as Pitsburg or Antioch - so Concord area is a happy medium