The size of your home does not matter.

Most take up 2 breaker slots so if you are low on slots, you might have to limit your choices.

I have one plus a UPS for my computers.

I have two of those. One on the main panel and one on the cable that goes to the submersible pump right where it goes through the foundation, downstream of the pressure switch. So that surge protector is connected to the pump at all times. Will they absolutely protect against every surge? No. Can I prove that they help in any particular instance? No. But do I believe that they are better then nothing? Yes.
I used the SquareD brand as I believe them to be as reliable, in general, as any.
But I have had a few SqD items that were bad right out of the box. Some brands have much worse experiences.

The instructions with my Leviton unit said to use two adjacent 20A single-pole breakers (not sure about their reasoning). Also, the closer to the top of the box the better.

@ronnatalie, I don't think a tandem/skinny would get both poles. Anything in a single slot would only be on one pole.

"The instructions with my Leviton unit said to use two adjacent 20A single-pole breakers (not sure about their reasoning)"
That gets both poles of your 120/240 service. A double pole breaker will serve the same purpose. For that breaker, amperages higher than 20 will work well also.

The only thing I can think of is this is one of the times where you might not want the handles tied. If one side of the supressor shorts (though they usually fail open) the other side could continue to work if it was still connected to a closed breaker.

> Can I hear some pro's & cons?

All appliances already contain effective protection. Your concern is the rare anomaly that can overwhelm that protection. Two completely different devices are discussed. Only one provides that protection that must even protect from direct lightning strikes.

First type is typically a $3 power strips with some ten cent protector parts. Read its spec numbers. If adjacent to an appliance, then it must somehow stop or absorb that energy. Destructive surges are hundreds of thousands of joules. How does that adjacent protector protect with only hundreds of joules?

It doesn't. Often a surge too tiny to harm the appliance will overwhelm and damage that adjacent protector. It promotes sales.

Second (whole house) type connects hundreds of thousands of joules harmlessly to earth. And remains functional even after direct lightning strikes. These are provided by companies with better integrity. And cost about $1 per protected appliance.

The second type device works because no protector does protection. None. Either a protector must somehow absorb tiny energy. Or, to be effective, it must have a low impedance (ie 'less than 10 feet') connection to what absorbs all energy. Protection is always about where energy dissipates.

Protection of structures is a lightning connected to earth. Protection of appliances is a 'whole house' protector connected to earth. Both examples are effective because they connect to what does all protection.

How good is any 'whole house' protector? How good is your earthing? Earth electrodes that only meet code can mean inferior protection. Protection is defined mostly by what absorbs that energy. Not just any earth ground. Single point earth ground.

At least one critically important number was provided. That 'less than 10 foot' is essential for a low impedance connection. Connection to and quality of the earth ground defines protection. Earth ground is why a 'whole house' protector can even harmlessly earth direct lightning strikes. And why a completely different device (also called a protector) does not claim to protect from typically destructive surges.

Parameter (the numbers) define useful replies. A 'whole house' protector must be at least 50,000 amps. In part, because lightning is typically 20,000 amps. These devices even sell in Lowes and Home Depot. But again, protectors are simple science. Your concern and most every question should be about the "art". What actually does the protection? Single point earth ground.