Whenever I install/update with the curses interface of aptitude, it keeps the log window open and asks you to press enter. Can I just let aptitude skip this and return to the main screen if nothing went wrong?
Having a look at the source code this isn't an option.
If you comment/remove lines 1218-1221 of src/ui.cc you can make it so, but if you think about it, I don't think you really want this behavior. If it jumps straight back to the UI you have no chance to view the output and make sure there wasn't a problem installing/removing the package etc.
Edit: just re-read your question and noticed you added the caveat to only do this if nothing went wrong. In this case you should probably submit the idea to the aptitude mailing list and ask if they'd consider adding it as an option.