Ofcourse A-kun is enjoying the trip, others are keeping the idiot occupied thus giving him free time to relax and focus on other things.
He even evaded the noisy disturbance outside his room earlier by sleeping in the same room as Sayaka instead and as a bonus getting a pleasant morning without Yoshiko trying to slobber all over his face. =p
In other words, he rarely ever get to be involved with Yoshiko as little as now, despite the two being on a trip together.