For all involved, he would be best served to take a deal. But the element of publicity for the DA's office is more than likely irresistible, he may not be offered one. This is a sensational case, lots of cameras. Unlikely to occur again in Weld county. And the economic boon to the area is also a factor. Hotels, restaurants, other businesses benefit from out of town news people.
This trial will go the distance, and is unlikely to be fast tracked, they will want every opportunity to benefit from the trial. Cynical yes. And probably very realistic.
Normally I would agree with you if the death penalty was a practical option. But because it's not I can see the DA accepting a deal for LWOP.