In May of 2008, Palestinian negotiators presented a proposal for a permanent border, with land swaps allowing Israelis to keep their West Bank settlements closest to the pre-1967 border. It was later leaked with the other Palestine Papers in 2011.
A comparison with Olmert's September 2008 "Napkin Map"makes it clear why the Palestinians thought the Olmert proposal inequitable.
A caveat on the Olmert map: Olmert was apparently treating this as his last, best offer, and was unwilling to give a copy of his map to the Palestinians unless they agreed to the proposal. A Palestinian negotiator was forced to sketch it on a napkin as a record. The map based on the Palestine Papers, evidently from a Palestinian source, is probably not perfectly accurate, but it does probably correctly reflect the broad intent of the offer.
It would have reduced total Palestinian territory relative to the pre-1967 borders, and allowed Israel to annex several salients driving deep into the West Bank. Also, it is unlikely that a neutral judge would think the swath of the Judean Desert proposed as part of the swap offered equal value per square mile to the territory Israel wanted to annex.
It's striking how little the proposed Olmert border resembled the one a rational defender would design when actually expecting a serious military threat.
For another attempt to achieve a permanent border by equitable land swaps, see the Geneva Accord.
Here is an interactive map looking at border options.