Having the height and another place to climb and play would be fun for them, and the textures of the platforms can be nice too. They can still scent mark with their paws even when declawed, so having an outlet for that even if it's claw-free can't do any harm. I don't have experience with declawed cats personally so I'm unsure what specific recommendations there may be for jumping heights, if any, but I think a cat tree would be good regardless. Bonus if it has a cubby or a bed to hang out in.