Neither Ron nor Hermione felt like going, however, so they and Harry wandered onto the grounds, still talking about the extraordinary events of the previous night and wondering where Sirius and Buckbeak were now. (22.2.1)
We find it really fitting and awesome that Harry and his friends choose to stay behind on the last Hogsmeade trip of the year. Harry spent the entire novel trying to go to Hogsmeade, and in the end it seems that the freedom Hogsmeade represented rather paled in comparison with the type of freedom he was able to give Sirius. There's even a sort of freedom in being with good friends that Harry discovers here; he doesn't need to go on a field trip to have that.