I would have liked to see a new series set in the Daedalus period following the end of the Romulan War when the Federation would be less than 20 years old. Obviously not a good idea to set the show on either the USS Archon, USS Horizon or USS Essex as fans already know what the fate of these ships will be from existing canon.
There is also that blank era between TMP and TNG which has many themes to explore such as first contact with the Cardassians, the Klingon Empire in the aftermath of Paxis being destroyed and buggering up Kronos in the process, the reemergence of the Romulan Star Empire as a serious millitary threat, Federation minor wars with newly encountered races (Katarans, etc.) mentioned in TNG and a host of other post TMP pre TNG historical canon mentioned during the show.