I'm looking forward to a high-gravity rocky planet that's possible to land on, but near impossible to escape. Like Eve, but much bigger (or more dense). This planet will be scary (and confuse) for anyone to try to escape. Also like EVE, you need to reduce the Delta V a LOT or burn up on re-entry. Duna is too easy for example.
EDIT: I guess "Ilve" is the largest inhabitable planet. But still a lot less mass than than what I'm describing.