That's a good question, Snoopy, and you are on the right track. However, the situps and abs probably would not do too much good - remember that, as a result of the lap surgery, they are cutting, moving and blowing air into your abdomen. As a result, I found my abs were pretty much shot. What helped me get up and out of bed and chairs was not my abs, but the rest of my body - my abs were essentially useless in the whole process. What was interesting, was the surgeon told me that people in good shape with those "washboard abs" are usually sorer because the musculature is tighter and thus stretched more by the whole air process.
What did work was that I had a wonderful trainer I was working with who had some physical therapy background. We worked for about two months pre surgery on strenghtening my back, my legs (which took the brunt of the effort getting up) and arms. We practiced getting up, moving in various manners, etc. I can't tell you the number of times I thanked him for making the movement after surgery an easier process than it could have been.
You may want to ask about getting a few visits with a physical therapist. They could help you not only with strengthening exercises, but also provide some good information and practice on how to get out of bed, how to get out of a chair, etc.