MAP,
Before springing for an automatic whole house generator you might want to price a grid tied solar system with battery backup. Whole house generators are initially very costly and will require both steady inputs of fuel and an annual maintenance.
A roll around is much less costly upfront, but you would need to be home during an outage to be able to fire it up and again require fuel and maintenance. If you do go this route skip using an essential load panel and consider having a slide lockout installed on your main electric panel with two main breakers, one from your generator and one from the grid. Not a bad way to go but you will need to be home if the power goes out to activate it ...not a good situation if you are vacationing somewhere warm and the power goes out in January due to an ice storm.
The most popular automatic solar backup system we install is the SolarEdge StorEdge. Most of the time the system will be providing you with most if not all of the electricity needed for your daily consumption, just like the grid. After the cost of the initial installation the power from the sun will be coming to you totally for free. At night the same battery that will provide you with backup power during an emergency will provide you with power that has been harvested that day and stored. In the event of a power outage the inverter will automatically disconnect from the disabled grid and switch over to the power stored in the battery. With only one battery there will only be just 10 kWh of storage with a peak output of 5,000 watts, but in most cases this is enough power to run your essential loads (heat circulators, well pump, refrigeration, some lights, internet, and ??), but you will be warm, comfortable, and connected. You might fully run out of power late one night, but the next day the solar will come alive again with the sun and power up your house and charge the battery for the following night. If the grid is down for many days, as it was in Moultonboro a few years ago, you won't really care. Here is a
wonderful short video that explains well how the StorEdge system works.
So how does this compare with going with a generator? A decent roll around with a manual lock out switching mechanism at your panel will run you about $6K, an automatic whole house generator will likely run you nearly $10K, and a StorEdge solar system will run about $30K before incentives. Currently you will be getting back $1,000 from the NH PUC and another 30% from the Feds, so your true cost after those will be closer to $20K ...and you will have free clean power from the day of installation forward, your house value and salability will increase in direct relationship with the cost of the solar system, and you won't be subject to the effects of oil surges and political whim for the next thirty+ years ( the solar panels have a 25 year warranty, the inverter 12, and the LG battery 10). Generally the payback on a StorEdge system runs about 12 years (after that the system has justified it's cost and the power is truly and totally for free), but that is totally discounting the value of your main pursuit, reliable, automatic, and constant backup power in the event of an emergency.
By the way, for those of you that read this and have island properties with permanent docks with circulators...