1) Either have more furniture already in the house, or have the option of buying and/or placing new furniture in the house.
2) Have some containers that are able to hold items, instead of having your items strewn about the floor. Even if there was some way to make the bookshelf/bookshelves hold books permanently and then function like the Mage's Guild library shelves do, that would be completely amazing.
Even after buying the house my mage has nearly 1 million gold left (and he didn't get any of it by exploiting anything...he earned it all through completing quests and selling honest loot). He's finished the main quest and now does odd jobs for the Mage's Guild and temple of Akatosh, and sometimes witch covens and daedra lords (rarely).
The house I bought has a bunch of rooms, most of which are empty and serve no purpose. There is one room that looks like a bedroom/study (has a bed, a table, a chair, a fireplace and bookshelf) and a storage-looking room (a couple sets of shelves and some boxes). Now, this is pretty cool in itself...I have a place to relax and sleep for free and practice my magic and read my books without interruption. If only I could appear to not be a slob by being able to store my stuff in boxes and shelves like a civilized person, and if I could furnish some empty rooms to accomodate guests or throw parties...ah well. I should count myself lucky that the option to buy a house is even offered in Daggerfall.