Hey Wife - welcome to the party!
I think it is awesome that you want to gift your hubby with a smoker, and I am going to reiterate a lot of what you have already heard. There are a lot of things you will want to take into consideration one of which is how much do you want to pay for a cooker, and how may do you want to have?? I think a lot of us have more then one cooker as we have progressed in our cooking. I agree with oldschoolbbq - decide on what you think you want and go one size bigger.
Unless he has been talking about a specific cooker, I would let him pick it out. The WSMs are well made, and relatively affordable. Take a look at a lot of signatures and you will see a lot of different cookers listed. It will give you some ideas for what is out there.
The one thing I think a lot of people don't really count on with stick burners is that bbq takes a lot of time - a big hunk of meat can take 12, 14, 18+ hours to cook. If you get something relatively easy to regulate (like a WSM) you can get some sleep - typically not so much with a straight up stick burner. If he's handy he may even want to build a UDS.
Good luck with your and his decission. Don't forget to circle back around and let us know how you made out.
BTW - you said you were the indoor cooker - you may just find this is something you both do together. Used to be Big AL wasn't interested - now he's out there cooking with me - it's a great way to spend time together.