Oh, where to begin. Where oh where...Christmas Special! Voyage of the Damned was the Christmas Special where the Doctor didn't have a companion but a space ship replication of the Titanic rammed through the TARDIS. They never did explain how that happened or how the TARDIS was fixed. I watched it, didn't have to, probably won't rewatch it.
Let's skip ahead. Donna Noble.
The overall arc wasn't about the Doctor (though it was, it really was) but more about Donna. His best friend, the woman who brought him back from the brink and gave him nothing but friendship to heal him and help him.
I really like Donna, she's brash, loud (really loud!), and forceful. And her journey is one to watch and love. Every companion who travels with the Doctor changes in some way. Rose found love with the Doctor and her compassion for others helped the Ninth Doctor change from a warrior to lover. Jack found his way from flitting (or flirting) through space and conning everyone and everything he could into a true hero--who looked great in just about everything. Or nothing. Martha found a sense of self-worth and courage she needed to be more than she'd imagined--she moved from grasping at her own imaginings and a slim hope at something with the Doctor to making her own life.
Donna is a tragic figure. She regretted her decision not to travel with the Doctor after her farce of a wedding in Runaway Bride and searched for him. She's still loud, still brash, and heaven help anyone who crosses her, but by the 2-part finale The Stolen Earth and Journey's End, she knows her own worth and how to use that to help. Mostly the Doctor, because that's what best friends do.
Her ending as a companion really was beautiful in a hopeless, heartbreaking, and utterly fitting kind of way.
Now then, The Doctor himself...there are hints at stories to come, at friendship and love and a future where he's not alone. Which is good, because he's lousy at being on his own. Makes too many mistakes, forgets why he's traveling and exploring in the first place, and why he visits and not just hides away and watches from the shadows.
There are hints at hope, even when he's absolutely crushed and saying goodbye.
The final episode is aptly titled: Journey's End. I feel they rushed the 2-part finale; better to have skipped Midnight (though it was a fascinating character study) and had the order be Turn Left (excellent story! Just...wow), then a 3-part finale.
Still, this was truly a goodbye. There's no one left. They've chosen different lives (Jack, Mickey, Martha, and Sarah Jane) or a life the Doctor has chosen for them for other reasons (Rose). And Donna. Oh, Donna. So important and yet so unconvinced she's worth anything at all. Your potential was finally reached, finally seen, and then...the end.
Once more a Doctor Who finale had the ability to make me cry. Excellent writing, excellent acting, and excellent...goodbyes. *sniffle*