Only because I fancy myself a creative person, here are my thoughts on a good ending to Glenn's story... (I am assuming he lived through the last episode, somehow).
Glenn gets bit multiple times by walkers but somehow escape the herd. His physical fight with the infection and turning into a walker is coupled with a mix of hallucinations and flashbacks (similar to Tyrese's death). The hallucinations include him making it away from the herd ok without getting bit. He also hallucinates meeting "Jesus" (the physical character from the comic and some religious implications, maybe a white aura around Jesus' head when they meet). The flashbacks include his recent memories with Maggie and learning she is pregnant and they are expecting their first child (from the comic). Both the hallucinations and flashbacks are coupled with Glenn's current struggle in the woods to return to Alexandria. He is "turning" but fights it off, focusing on seeing Maggie one last time.
Note that while in the woods Glenn DOES meet Jesus and this meeting is sold to the TV audience as a hallucination but it actually happens.
Glenn story ends when he arrives at the gates of Alexandria. This arrival is coupled with (and TV edited with) one last hallucination. Glenn slowly walks over a hill and into Maggie's arms, a hallucination of a happy ending with a brief story about how he escaped. In reality, Glenn does arrive at the gates of Alexandria in a much different way. The camera close on his face, and with all his strength and the last bit on humanity left he utters the words "M...M... Mag... Maggie." He then yells "MAGGIE". (his last words are straight from #100 of the comics). Multiple tenants of Alexandria hear him yell including Maggie, but knowing immediately that is it Glenn, she is able to run faster than anyone, fueled by adrenaline, to get to the gate first. She gets to the gates, pulls it open to see her loves fate. The TV viewers see for the first time how bad Glenn's injuries are at the same time Maggie see's him. He is overly bloody and being carried, a motionless rag doll, in the arms of Jesus. He is clinging to life and his wounded are clearly fatal. Jesus hands Glenn to Maggie. Maggie takes Glenn into her arms. He is still alive but barely. They share a glance, they do not speak. Others from Alexandria arrive and are seen reacting, in slow motion behind Maggie. Glenn and Maggie are reunited long enough to for him to die in her arms. Fade to black.