Good decision. One of my favorite quotes concerning the job you're leaving comes from columnist Bob Rosner: "Don't think of it as your old job, but as your newest reference."
After you get your new offer in writing, compose a civil letter of resignation and meet with your boss. Or you can resign verbally and leave the letter. Say your new job is too good to pass up. You appreciate everything you learned while at the old job and will work to help train your replacement, or otherwise ease the changeover anyway you can.
As you recognize, there is absolutely no advantage to not looking as good going away as you did coming in.
DEAR JOYCE: After resigning from my crummy job to enter law school, I was asked to sit for an exit interview. I see no reason to tell them all the things really wrong here, including the department manager, whom I hope to never see again. -- S.B.
Nor do I -- from your perspective. You admire the company. You admire the boss. You admire the coworkers. Even when you feel like shouting, "That's it, I'm outta here," there's no sense making enemies who could come back to haunt you years later. Short-lived satisfaction isn't worth it.