Oh that's tricky.
I think I would go with atmospheric landing though too..
Thing is, I think to do that well might be more challenging than space legs. At least with space legs you can come up with a few tasks and bits and bobs to do and have these operate in a relatively restrained way in (and around?) your ship, on stations and _maybe_ on planet surfaces.. Good atmospheric landing by itself probably isn't a huge challenge, you want some interesting in atmosphere flying stuff (tricky but fine) and some pretty graphics (time consuming, resource intensive but fine) but then having lots of interesting things on those planets to do and see is going to be time consuming I think. Unless people are happy with atmospheric planets that are also relatively baron, I reckon we could have that relatively cheaply. As soon as we talk atmosphere we end up at terrestrials and then we get in to the whole 'how do you do cities (or other settlements)?' and 'what about all those trees and animals and stuff?'. That is time consuming and challenging.