Different tire brands/models will vary with regard to noise levels, grip and overall life. It is important to know what type of tire you need. All seaason, summer and so on. You can learn a lot about tires on this website;
Tires at Tire Rack
The overall ride comfort is affected mostly by tire size, but seeing as you are stuck with the size because you already have the rims, ther isn't much you can do about this.
Spacers make a visual difference and maybe a slight handling difference seeing as they push the wheels out a little further for a wider stance.
Actually, this link will take you where you need to start.
Tire Tech Information - Selecting the Right Tires