Just bought a house and will be moving in in a few weeks. I'd like to epoxy coat the garage floors right off the bat while there's nothing in there. I was looking at the Rust-Oleum RockSolid floor coating, my garage is 456 sq. ft. and it says it covers 450-500 sq. ft. of area.

Has anyone used the Rust-Oleum floor coatings in their garage? How well do they hold up? Any tips or tricks for a good application? What about the flakes, is it easy to apply them evenly so that it looks good?

I used the epoxy shield  kit that they offer and it works great. Did it 2 years ago and going strong. I recommend doing a clear coat with anti skid additive so that way you are not slipping and sliding when your shoes are wet. As far as the chips go I did my best to get them evenly but it is all up to you.

Prep, prep, prep.

You need to follow the prep instructions, Muriatic acid?  Etching?, deglazing?

Nothing will stick without the proper preparation.

Ucoat It.
It's pricey, but it's some of the best product out there.
I've had it on the floor of my working garage for over 10 years, it is holding up well against welding, grinding, oils, etc.
All I need to do is mop it every now and then
Do the preparation exactly as they tell yo in the DVD.
When you think it's clean enough, go back and clean it again.
I used a light gray color as my top coat and it really brightens the garage up.

This. It's easy to roll on once the prep is done.

Pressure wash
Scrub and remove oil/grease stains
pressure wash again
Let dry 24 hours
roll on epoxy coating from box

Also I recommend getting that synthetic sand stuff you can mix inside to make it grippy...I didnt know this was a thing when I did mine and I've almost slipped like 10 times in a year when it's wet.