I would also point out that as far as canon sources are concerned, I don't recall ever seeing anyone get force "moved" in relation to an attack. If they could do that, why wouldn't vader have just thrown Luke instead of chucking air conditioners at him? Why wouldn't Palpatine have chucked Yoda? Or Dooku have thrown Yoda... it had to be easier then bringing the roof down. Even in the clone wars cartoon, I don't recall seeing it happen. They threw droids (objects) around, but droids are not "beings". I've never seen them throw a being. I've seen them save people with a force "catch". Obviously, Vader could lift people while choking them.... so I don't really have an answer. Maybe The Force just doesn't allow it.
The only place I've ever seen someone flat out get "moved" was in the force unleashed (not canon).
Actually we see three instances of people being moved with the Force in Revenge of the Sith alone
First one is Dooku, who Force chokes Obi-Wan while lifting him into the air before hurling the Jedi Master away.
Second one is Yoda throwing Palpatine several meters through the air and over his desk to land ass over tea kettle in his big chair.
Third one is Obi-Wan and Anakin's "force push contest" during their fight on Mustafar, which resulted in both of them being hurled away from one another.
We also see Dooku using the Force to move/toss Anakin aside while electrocuting him with Force lightning in AotC.
We see Maul doing a "Force shove" against Obi-Wan in TPM to toss the headstrong young Jedi into that pit during the Theed lightsaber duel.
As for why it's not a "go-to" tactic, especially against other Jedi of similar skill and power... well, take a look at what happened to Anakin and Obi-Wan in RotS, and now imagine that occuring if they were both out on a catwalk that stood over one of those rivers of molten lava.
And in the case of Yoda, he's demonstrated on a number of occasions that attacking him directly with the Force isn't going to work out so well, since it's quite possible a sufficiently capable Force-user can just rebound your Force attack right back at you. Dooku likely tried hurling chunks of the ceiling in the hopes that Yoda wouldn't be able to catch all of them, particularly after having one of his Force lighting attacks bounced right back at him and the second one simply negated without all that much effort. Palpatine likely felt the same, and aside from being drunk on the dark side ("Unlimited POWAH!!!!!") hurling the Senate pods worked to keep Yoda off-balance and constantly moving and thus unable to close to lightsaber range, where he very well may have had the upper hand (particularly since Palps seems to have lost his back-up lightsaber at some point).
The thing to also remember with the original movies is that Lucas was working with somewhat more limited technology and the fact that the Force wasn't quite as "fleshed out" as it is today. I remember being a pre-teen when RotJ hit theaters, and the sense of awe and worry when the Emperor suddenly started firing lightning from his finger-tips and began flash-frying Luke. We never really see Vader in the original films cut loose and start busting heads; he was wary enough of Obi-Wan to not try anything too flashy (considering where it got him the last time they fought), and in his fights with Luke, the goal wasn't to crush the boy but to turn him to the dark side. In Luke's case, in ESB he's barely trained and not really that savvy with what the Force can accomplish, and while he's much more comfortable and capable with the Force in RotJ, his goal when fighting Vader is to redeem his father. Although during the Pit of Karkoon sequence, we do see Luke using a "Force Kick" (i.e. a fight scene failure) when he kicks at one of Jabba's goons as Boba Fett goes soaring past in the background, and there's a good couple feet between his foot and the goon, yet the goon goes flying backward. Again, it's simply a case of mistiming in the fight coordination, but it could technically be counted as Luke using telekinesis to push an opponent back, using his foot as opposed to a hand gesture.