Ragu Homestyle meat sauce, which worked nicely.
Seems kind of silly to cook less than half a pound of the spaghetti at a time, so I had basically an entire day of eating nothing else. Wouldn't do it every day, but it's fine as a change of pace. Probably get some meatballs to add in next time, too.
All that, and I still have another box of spaghetti to use up. Think I'll wait a couple of weeks before doing something like this again. Much as I like my pasta, several days of basically nothing but spaghetti is a bit of an overload.