I think you will find it hard to get a dog that can do both very well. Beagles make great rabbit dogs but very few have enough tree instinct to tree coon. I have owned a couple beagles that would tree squirrels as well as run rabbit but their tree style would never work for coon. They would run the squirrel to the tree lookup for a minute or two then leave to find another one. In coonhunting the dog may have to hold the tree for extended periods while you work to get to it. If you are deadset on getting a dog that will do both I would suggest looking at the curs or feists as these are some of the gamiest dogs around plus they are tree dogs. I am a coonhunter that hunts walkers and one of our toughest things is to break hounds from running off game so I do not recommend trying to have one dog do both you might have a dog that runs rabbits at night and coon during the day.