^ I would like to see something on Indra Dev, since he is portrayed to be a God who made many mistakes, got cursed, and whose arrogance was destroyed by Krishna not once but twice or thrice. At the same time, we all pray to him because he is the God of all Devtas. It would be interesting to see a serial centering Lord Indra as the main character, and show all the stories from Krita Yuga, Treta Yuga, and Dwapar Yuga that involve him (Ahalya, Govardhan, etc).
I would also like to see something on Brihaspati and/or Shukracharya, the Guru of the Devas and the Asuras respectively. A serial based on the other avatars of Vishnu would also be good, but I guess nothing else is really as long as Ram or Krishna avatars so it would not run for long even with added fluff.
Oh, and I almost forgot. A serial on Maharshi Narad would be so interesting! As he's my favorite rishi, I would love to see all the stories that center around him, including why he got cursed in the very beginning of his life.