There is an "easy" solution to this problem, and whether they arrive at it quickly will be an excellent indicator of whether these two parties wish to make a deal. (The alternative is that they just showed up to please the US and President Obama but don't really care to do it.) The solution starts from a recognition that the draft settlement that both sides have seen and studied allows for some swaps of territory: some of the West Bank going to Israel, similarly-sized swaths of territory going from Israel to the proposed new Palestinian state. Further, most of those land swap areas have already been identified, and for the ones going to Israel, well-populated already with Israeli settlers.
All that is needed is for Israel to draw conservatively the map of territories they are due to get--conservatively meaning not aggressively, i.e., not including within the zones land that that is disputed in previous negotiations--and announce they will only build new settlements within those zones. The PA does not have to agree to the specifics of these zones of new development at the present time, but merely to tolerate it.
Such an "agreement" would be a great starting point for future negotiations; essentially, they would agree to take a large set of potentially contentious content and put it in a briefcase of agreed topics. One of them would be the PA's contention that all the Israeli settlements in areas beyond the 1967 boundaries are illegal. It would also put the framework of the discussion into a new agreement rather than trying to re-create the status prior to 1967, which was an unacceptable one for Israel.
Two cautionary notes, though:
1) there would probably not be much agreement on new settlements in East Jerusalem, and the Israelis would be well-advised to be extra careful about targeting any new areas there; and
2) Sharon's Wall--the safety wall the Israelis have been putting up in occupied Palestinian areas to separate priority zones of Israeli interest from the Palestinians--could easily be a complicating factor. The Israelis are unlikely in this scenario to identify much beyond the Wall, but neither should they assume everything on "their" side of it is agreed (especially if it had not been agreed in the draft maps of prior negotiations).