In my experiece, the strut tower brace actually did improve the ride a lot. My car rattled and flexed horribly when I went over a certain deteriorated expansion joint on the way home from work every day before the STB, but after, it just makes a gentle "thud". Keep in mind, this is Michigan, so you know the road hasn't gotten any better...
And of course, the handling is a bit tighter too.
Whatever you do, and whatever you want your car to be, I would highly recommend doing the STB. The car will just feel better.
Oh, and I say just stick with the suggested PSI on your door. On mine, it'* 30 all around. Anything less and your tires will wear funky and your mileage will be hurting. Also, like the man said, stay away from low profile, stiff sidewall, performance tires.
If all else fails, sell it and buy yourself a Buick Park Avenue.