I also considered paying six months or more upfront for a discount – but then I realized I would be stuck here for six months at least (in case a much better rental became available), plus, if something broke, the landlord would be less likely to make a timely repair since I would not have the leverage of withholding a portion of the rent to get the repair done myself.
The whole place could go up in flames as well. Also – with that kind of cash, why not put it in a six-month CD instead of your landlord’s wallet?