My last home, I used the Home Depot "do-it-yourself" gray coating with flecks. It actually went on fairly well and had you etch the floor before application to ensure it stuck. Unfortunately the flecks weren't even since I did not know how much to apply...heavier in beginning and lighter as I was running out. No tire peel was experienced, and we do live in a hot climate. The no tire peel impressed me from a inexpensive product. The only thing missing was the high shine that the professional applications take on.
My current home, I had the coating professionally applied. I have one spot where hot tire peel occurred. The contractor warranty's the work so it will be repaired. I was a bit upset though since he did not fully seal my joints where the stemwall meets the slab and in fact forgot that I had asked him to apply on stem wall, below the sheetrock. The look is much glossier than the do-it-yourself and there was no way I was going to do an 1800 sq ft garage by myself.
Things to look for:
*If your garage gets full day sun - make sure that they use a UV safe product so it does not change color
* If you do a lot of mechanical work or work with small screws, nuts, etc...you may want to avoid the flecks in the base coat. The flecks at the last house drove my DH crazy if he dropped a spring or screw. We would have to get on our hands and knees to try to ind it amongst the flecks on the floor.
* If you choose to go with a single color, make sure to ask for some non-skid stuff on top since this can be extremely slippery when wet. I think they use a silica sand for non-skid, it retains the gloss, just adds some resistance when wet.
*Make sure they seal the joints with an elastic sealer. Find out how full the joints will be filled. My do-it-yourself, my joints were quite full and helped me clean the floor. The joints in the middle of the garage are filled, but barely and still leave deep grooves for stuff to collect.
*if you have stem-walls that you want coated, make sure it is included in their standard price - many have this as an option and add to their bid.
* What is their warranty? Are there temp restrictions to application time? This is especially tricky in AZ since some application products advise not to use above certain temps....even though the contractor may warranty it, will the product manufacturer back it if it is not applied correctly?
*Plan to not be able to park in your garage for at leats 72 hours or more to allow the product to cure