What, if any, impact will the light rail have in desireability/resale in both Denver & suburbs?

Definitely it will attract more to the area as the homes will be less expensive . Its like subways lines in major cities. It makes the commute easier. I doubt whether it will affect the desirability of living within the city limits.  

With more and more transit oriented communities being developed in the Denver area, the dynamics of suburbs and downtown living areas will no doubt undergo several changes. Increasing gas prices, and oil shortages will inevitably lead people to look toward living situations that will allow them to easily commute to work, life, and play areas. Remember, a bigger house means bigger bills. It is up to developers to create communities that allow all socioeconomic conditions to be part of these new living communities. Different people will be attracted to diverse areas in the Denver metro areas. This means that some areas will suffer from the changes while other areas will experience quick prosperity. Specifically, the addition of light rail will cause prosperous growth along its routes, and help to connect communities. Downtown areas such as the newly developing Union station district will experience a boom in population and land prices, specifically among the young, hip, and wealthy populations. While the outlying areas will increase with families, and middle class populations. Denver will continue to grow and prosper in the near future, it is up to the polis of the area to create responsible growth, increase density, and manifest diverse communities if that flourishing is going to last for the long term.