This sixth season of the show is an odd beast in several ways. Unsurprisingly for such a long running show, it seems to be having issues with generating sufficient plots to fill the time, and at the same time the many actors involved in the show have only grown in fame as a result of being in it, so there is pressure on schedules to get everyone to stay involved. We have all seen shows that run for a long time and struggle to keep viewers because, while essentially the same show, the feeling of treading water sets in and fickle attentions drift off.
When this happens you will see things happen similar to what Troy McClure introduced for the fictional 'next season' of The Simpsons; for instance people having babies, novelty episodes set in different locations, and so on. In this regard, the sixth season does a lot of that – three different pregnancies, several episodes on the road, and quite a few big name guests to keep things high in the interest and ratings. For the most part all of these are obvious for being what they are, however somehow it doesn't really matter because mostly the show remains funny and lively. So there is that odd clash of knowing that it is playing all the tricks it can, but yet at the same time you appreciate it doing what it needs to do to keep things moving because it does remain funny.
That said, I note the next season is not only the last one but also about half the length, and although I found this season funny, it is hard to see this as a bad thing that it draws to a close.