A lot of people talked about memories of Guts with the Hawks....
Personally I was never able to really find those moments "happy". Sure, everything looked like it was going well, but I was never really able to accept that Guts was in the right place in the Hawks, mainly because of the 'dirty work' he had to do for Griffith. He kills a kid - even if he accepted what Griffith asked of him and did it, it clearly affected him; he tells Casca, IIRC, that he doesn't want to be 'weighed down by another man's dream' (or something to the gist of that).
Griffith undoubtedly had most of his successes thanks to Guts. Nearly every later, more important battle with the Hawks involved seemed to place Guts, not Griffith, as the most important strength of the Hawks. Yet Griffith's achievements, through Guts' work, are viewed as higher and more important; Corkus even blames Guts for the Band's fall, but without Guts, would the band have ever achieved the 'White Phoenix' position? Considering that Guts carries the value of Casca in addition to himself (having saved her several times in quick succession against Adon and the 100 men and so on), he's IMO much more important than Griffith to their success. Griffith wins battles based as much on the stupidity of others as on his own ability - see Doldrey, where he asks for too few troops and only wins because the main commander is stupid enough to leave the castle without suitable defense.
Because of all this I can't really accept any of the scenes of proposed happiness with the Hawks as bonafide. I'm definitely with the reunification with Casca after beating Mozgus. That of course is quickly marred when Guts nearly rapes Casca shortly afterwards, but at the time it sure felt happy.