Is the best possible "Happy Ending" you can get (non-sacrificing your Grey Warden) is romancing Lelianna & (via the credits) finding out you're traveling the world with her after it's all said and done?
I ask this, because I've found that the vast majority of the endings are a depressingly horrible, yet awesome, collection of very sad endings in which:
1) You die to save the world
2) You die to save the world & lose a future with Lelianna (but get a double whammy when you find out that when she dies, she says she'll "Finally be reunited with her love..."
3) You die to save the world & lose Morigan (yes, she is in love with you)
4) You let Allistair die to save the world, so you can live & be with Lelianna
5) You let Lohgain die (big whoopie) to save the world so you can be with Lelianna
6) You perform the Blood Ritual with Morigan so you can live, kill the dragon, so you can be with Lelianna (and also find out that Morigan does love you, even though you never romanced her)
See where this is going? There's several other possible endings (all small variations on a common theme: You save the day, but ultimately, still lose something important. I'd honestly would have loved to have had the option of a very difficult to attain ideal ending. Something in which Bioware said "Okay, you nitwits want a "Rainbows & Puppy Dogs ending, eh? Okay, you have to do this, 100% in order to get it." To me, that'd be the ultimate goal to shoot for & all the other endings, what I replay the game to experience.