You've gotten a lot of great advice so far but if I may add I'm in a similar situation as you so you are not alone my friend!
My current struggle is converting our garage (which has never seen a motor vehicle in it (as far as I know except for my motorcycle) into my shop. I've spent a good fair amount of cash on tools and would really like to be more involved in my "hobby" (as my wife refers to it) or at least a place to use those tools. I guess it is a hobby as I have no intentions of making a living doing it. Anyway this has been my biggest struggle, it's a 19'x17' space and is completely unfinished on the inside. I have all these great ideas and plans to make it my space as I and George (one of our dogs) are the only males in the house!
I love my wife and bless her heart she puts up with my silly interests one of which is woodworking. She also has a respect for her grandparents whom she bought the house from years ago before we were together.
Unfortunately that respect sometimes gets in the way of us making some much needed improvements on our home. For example, in the garage there is a workbench that's in really bad shape, soaked with oils and other chemicals and would fuel a fire for weeks and I would love to remove it, along with the real low hanging shelves that are well, in the way so I can put new benches in there. This bench was put in by her grandfather and she doesn't want to get rid of it for that reason and causes a huge uproar whenever I mention updating the garage. In my design plans I've also incorporated storage for all of her stuff so it's organized and easy to get to but this hasn't helped much.
As jay mentioned doing stuff for her is you're biggest benefit. It's her "ROI" (Return On Investment). i actually have a lot of projects lined up to do for her that I know she wants done but it's kind of hard not having a place to do it in.