I'll give you my list of some house mods I've used. All have lots of storage space.
http://www.fallout3nexus.com/downloads/file.php?id=9592 - Probably the most popular house mod out there.
http://www.fallout3nexus.com/downloads/file.php?id=3644 with http://www.fallout3nexus.com/downloads/file.php?id=6686 to redecorate it - Big enough to get hopelessly lost in but it has auto-sorters which every great game hoarder needs.
http://www.fallout3nexus.com/downloads/file.php?id=1663 - I use The Lab version. It has a great workbench room with alphabetically labeled containers for sorting your components and they're all within close reach.
http://www.fallout3nexus.com/downloads/file.php?id=2722 - This one has a couple different versions depending on where you want to live. The one I used was by Bethesda Ruins for a Raider character.
http://www.fallout3nexus.com/downloads/file.php?id=11156 - Good amount of storage, conveniently located and big enough to comfortably house two or three companions too.
If you're looking for something to spend your caps on:
http://www.fallout3nexus.com/downloads/file.php?id=13517- Huge vault with a pretty fun quest to obtain it.
http://www.fallout3nexus.com/downloads/file.php?id=13660 - Requires Point Lookout.