In every season (of the new series) they have one episode in which the doctor has just a cameo and that focuses on something or someone else.
Yes, it's for production reasons. They also invariably do something similar for the companion. The filming time for Tennant and Freeman during Blink allowed them to film the finale, for example. Catherine Tate's absence during Midnight was to allow her to film Turn Left.
Blink introduced the best monsters of the entire Whovian universe, IMO... the weeping angels are, well, in a word, terrifying..
Yes, I think I agree with that. Having seen pretty much the entire canon, they're the only monster that won't date and become lame - and not need a reboot. The Daleks, in every incarnation, were not particularly scary (for me), though the fringe variations like the Special Weapons Dalek make it interesting. The Cybermen were creepy the first time I saw them because I knew they were made from people in some fashion - and the reboot made better Cybermen, but still not scary.
All the others will generally need some kind of reboot at some point in their future to keep them relevant (the Daleks have long since ceased to be relevant, and really the only time in recent years where they were particularly interesting was when Davros was with them)
The doctor's companions in the new series have been hit or miss, though....
Rose (season 1) good... the rets of the time, she's a whiny, lovestruck twit with no good plot
But even in season 1 she's still a whiny, lovestruck twit. The finale to season 1 is definitely redeeming for her though.
Martha - probably one of my favorites from the new series - but under plotted and wasted
The plot from Family of Blood was pretty good, and played quite well I thought, her part in the season 3 finale was certainly her finest hour, and the parting of the ways between her and the Doctor was very good. But yes, under-plotted and wasted.
Donna - hated her (but then again, I dislike the actress)
I don't like the actress much, I didn't particularly like her role, however I did appreciate the character development - that by the end of the season she had changed, and her fate is all the more bitter because she'd become a character I didn't thoroughly dislike.
Amy - meh... she's cute - but they tried to make the show more focused on her and that annoyed me.
That's the thing, though, the whole point of the show, really is that it isn't about *him*. It's the story of his companions and the worlds and tales he shows them - it isn't his story, at least not from my perspective.
Jamie - one of the few male companions... interesting fella.
Feisty fighter, shame that his mind got wiped really.
Sarah Jane - probably the best, most developed companion ever...
Certainly the most developed companion in Old Who. Nice to note that by the time we got to New Who and met her again, it wasn't the same dynamic as before - it was much more on an equal footing.
Teela - kick-ass barbarian!
And one to whom everything the Doctor did was 'magic', which got old a bit fast.
Ace - possibly the worst companion ever
Not even close, seriously. Don't forget, at the time Ace was the companion, the BBC were desperately trying to shut down Dr Who quietly by making it increasingly crap, combined with a script editor who was trying to push a political agenda in the background. She had the same problem Colin Baker had some years before - bad scriptwriting. Ace's overall character arc, the Curse of Fenric and Ghostlight is actually very clever. Survival, however, is a truly dismal storyline.
Romana - cool... possibly a little-basis for River Song...
Yes, very much so - her later character, not the younger form we see taking on Hitler! But yes, her later approach once she's become a Doctor herself, does have similarities to both incarnations of Romana.
If we're debating characters, Peri 'Perpagilliam' Brown, the only character to manage to overshadow the regeneration of her Doctor, with cleavage >_>
But worse than that, Mel. I don't even know Mel's last name, but dear god, irritating. Trying to get the Doctor to drink carrot juice >_< This isn't funny, people. Or Adric. You can't convince me Ace was a worse companion than Adric. There is a reason Adric died, and not one of being dramatic.
Tegan Jovanka (Four and Five), Turlough Vislor (Five), Nyssa (Five) were all perfectly adequate, even if Turlough's back story is way more convoluted and unnecessary than it needed to be (tied into the whole Black Guardian mess), though like most of the characters that far back, there wasn't a great deal of development for them.
Going a bit earlier, Liz Shaw, Sergeant Benton (Three) and of course the Brigadier were strong characters too - though only the Brigadier got any real development.
