I agree with you on the tangential conversations, and the dead space is indeed hard to fill, as it were. But yes, I believe this is achieved in Plan B. I think the problem with Weekend is that I simply did not like the characters so any tangential conversations they were having did not enamour me.
Ah, but you see, I do think it is absurd to see a straight guy falling for another guy! However, it could be argued that he merely hadn't realised, or had denied, his sexuality, but this isn't what I meant by absurd. What I was actually referring to was this whole 'I'm going to seduce my ex-girlfriend's boyfriend to prove he's gay so I can win her back' thing. These types of things are buyable in films like Dangerous Liaisons or Cruel Intentions, etc, but not in a film which is striving to be so naturalistic; added to this is the fact that the film is, in my opinion, a little ham-fisted in advancing this, well, narrative device. The conversations the hairier fellow has with his friend I found to be a little obvious in their intention and that grated on me.
The cinematography! Well! The thing is, I didn't feel a sort of gritty realism in it, as in say, 'A Beautiful Thing', I found it to be more akin to a drunken 20 year's old digital camera footage from a crazy week in Malaga.
Haha, I sound like I hated it! But I really didn't! I actually really liked it. The characters, acting, and, somewhat, the script, really were quite brilliant!