Alright, I've thought long and hard about this. What Harry would do for Hermione on her birthday:
It would start out by Harry accompanying Hermione to the Great Hall for breakfast, where he would have prearranged for everyone in Gryffindor to sing "Happy Birthday" to her. Then, after breakfast, he would escort her to her first class. In between classes, he'd give her a rose until he had given her enough for every year they have been friends. Around lunch, he'd drop by and see Dobby for a quick visit and then rejoin Hermione underneath their favorite tree by the lake and he'd listen to her talk until classes began again. After classes were all over with, Harry would scribble down notes and leave them lying around in the common room for Hermione to pick up. They would eventually lead her to Firenze's room, which is set up like the forest remember, and Harry and Hermione would share a candle lit (or fairy-lit) dinner. Later, they would have cake, which was the reason why Harry went and saw Dobby. Before they leave, Harry would give her a small gift

which Hermione would open to see a sapphire ring (as it's her birthstone). He'd then promise to be there for her forever and maybe, just maybe, he'd give her a small kiss on the cheek

and whisper, "Happy birthday, Hermione," in her ear.
What do you think?