In the Voyager episode "Resolutions" the doctor puts Janway in stasis for 17 days. Why did he put them in stasis when he could have had Janeway helping out by analyzing and working on a cure during that time?
The virus was only dormant or suppressed on the planet, not on the ship. The Doctor lacked his mobile emitter (having not yet received it) and couldn't work on the planet (nor could any other crew members, given risk of exposure to the disease). Janeway couldn't work on the ship, as it was implied she would begin to suffer the symptoms very quickly if she were to leave the planet.
Janeway is a capable scientist and researcher, but she is not specialized in the medical fields. While I'm sure she could have been useful (and could possibly have succeeded in discovering a cure with Chakotay, given enough time on the planet) in helping the Doctor, her assistance would not have been irreplaceable. Most of what the Doctor could have needed an assistant for, Kes was able to do. There's also a question of what she could have actually done from the planet's surface, given that they would have had to set up a research station and worked separate from each other.
Recall that the actual setup of the equipment took a significant amount of time when Janeway and Chakotay did it later in that episode.
Now consider the risks of having Janeway awake on the planet - she could have been exposed to more diseases, she could have been at risk from large predators, she would have needed to be provided with supplies, and there's always the risk that the disease could have worsened to the point where she began suffering its effects while on the planet.
Given the risk to reward ratio, it's entirely understandable that she and Chakotay would have been kept in stasis until the chance of a quick cure faded.