The next round is just for the play off teams, teams that were positioned from 8th to 1st will be relaxing. For Lille and Aston Villa, though they had easy teams as you said, but they really tried in beating them and getting to the position at which they found themselves now. It likely that the Play offs will start in two weeks time.
Lille and Aston Villa are doing a great job, both teams are destroying their opponents with big scores and they deserve to be where they are. Well, the match in the play-off phase should be much more interesting, because the teams that enter this phase will be required to play much more seriously and bring out their abilities in order to advance to the next phase. But in reality it will not be easy, because they have to maintain their fitness and performance with of course the increase in their match schedule across competitions. On the other hand, the teams in 8th to 1st positions can focus much more on other matches, for some teams will focus on their domestic leagues while preparing their performance to welcome the return to compete in the Champions League. Honestly, I can't wait for the teams that entered the Play Off session to start their matches in this competition again.