I'm not sure if the implication in Looking to Tomorrow is that Mayu and Saki got together, but I'd like to think it's just regular embarrassment, because I think the ending to the main story is great. Mika and Mayu ending up together would've been a perfectly fine conventional ending, Saki and Mayu ending up together would've been fine if a bit surprising (how often does the third wheel end up winning?), but I never would've expected an ending where they all stay as friends. I was disappointed for a minute, but after thinking it over for a bit, I decided I really liked it. This ending isn't even bittersweet, all the main characters end up happy. They all grow as people, they grow as friends, and they grow to understand their sexuality better.
The side story is a bit wacky, and I probably wouldn't have it enjoyed it that much if it was presented on its own, but it gives a nice contrast to the (by comparison) more cerebral main story. I really don't like Yui, but I understand where she's coming from, y'know? I assume she's the straight* (possibly) character mentioned in the first volume's author's note.