I'm glad your son is headed to rehab. I hope that he comes to realize that it is precisely what he needs--to be on the path of staying clean and sober. Rehab was a good experience for my son. It's early in my son's recovery (only a couple months) but he certainly appears to be grateful for his being drug free at the moment.
One thing people here encouraged me to do was to find a sober living house for my son when he left rehab. We didn't do so because my husband was against the idea. I can see the value in such places, though. I think it's too easy for our children when they come back home. My son has not caused any trouble since he's been home, but he's not as motivated as he would be outside our home. He's too laid back now IMO. He would be more responsible living somewhere else. My goal now is to see he gets out of our home as soon as possible.
A sober living facility would give your son some structure to his life right when he comes out of rehab along with some independence. You and your husband would not be put in the position of having to be the ones checking to be sure your son does what he needs to be doing. Please consider such a place seriously.