* Base rent - The obvious starting point.
* Utilities (water, electric, gas) - Electricity was going to be a factor wherever I went, but whether or not I footed the whole bill or split it with others factored into my monthly costs. Similarly, some places where I was looking had a well, so I wouldn't have had to pay for water. Finally, some places used gas for cooking, or for winter heat, so I estimated those costs and included them as needed.
* Cable & internet - Some places I'd have to cover the whole cost by myself, but in others I could split it with other tenants or the landlord. Depending on the final cost, that also told me whether I should opt for cable or just go with streaming what I wanted to watch.
* Laundry - if a place didn't have its own washer and dryer, I was figuring at least $30.00 per month to go to a laudromat.
* Mileage - I hopped on Google maps and figured out the distance to work, then calculated on average 21 working days per month at 32 mpg that my car gets times $3.50/gallon, which is where gas is right about now. It doesn't include any driving otherwise, but that will vary from month to month anyway, whereas work won't.
* Storage - I have a small storage unit, so the size of the place determined if I needed to keep it, or if I could close it out and lose that extra monthly expense.
In the end I realized that the place that I wanted, which had a base rent only marginally higher than the place I ended up picking, would have actually been almost $200 a month more once everything else was factored in.
Did I miss anything? I hope others find this kind of list useful! :)