Mawrth Vallis - good choice.
I've thought possitive about this region:
http://mars10.jpl.nasa.gov/msl/mission/timeline/prelaunch/landingsiteselection/mawrthvallis2/
Then, there's Holden, a VERY old crater, but that can be a good thing (providing we dig deep.... Mawrth Vallis hold promise.... please, DIG!!!!
