The choice to put Catherine in charge makes sense in terms of seniority, etc. The only one above Catherine is Grissom, if I remember correctly from that episode with the guy who killed the wannabe showgirl... So, putting Catherine in charge makes sense, but I do agree she can get a little bossy and overbearing.
And, if they do go forward with a 8th season without Grissom, she needs to start to work on that, maybe become aware of it. I mean, if we get to see her actively working on that, it'll endear her to more people and show some personal growth. Also, it'll hopefully make her less bossy, and that's always a blessing.
As for the promo, The Warrick/Grissom conversation is going to be interesting since they really haven't had many meaningful moments since season 3. The Nick/Grissom hug looks Nick initiated to me. Either way, it's awesome. As for the "I'll miss you," I think it's to Sara just based on the background behind him in the two shots.. but I am SOO not positive. Though, if it is, I see it along the lines of the change from "The lab needs you, here" to "I need her." I could see him saying that to her alone where he might not have in the past.
It's going to be heartbreaking. It really is. I don't think I realized how important Grissom was to me until I was watching that promo. Every time he says, "I'll miss you," it breaks my heart, because we're going to miss him.
My fiance says there is no CSI without Grissom. Matthew has watched since the beginning, owns all the DVDs, etc. His favourite character is Warrick, but he says there is no CSI without Grissom. I guess this upcoming "break" will give us an idea of whether or not that statement is, indeed, true. We'll see, I guess.