Sip a flute of Champagne Laurent-Perrier Brut at $15 a pop. Nibble on a stack of silver-dollar wild-mushroom pancakes served with a delicate balsamic vinegar syrup. Sit back in your chair and settle into a happy sunlit Sunday groove. Under the influence of tasty food and effervescent drink, the mind kind of dilates during the Astor's gospel brunch. When Maryel Epps arrives still wearing her choir gown direct from performing at Unity on the Bay, you want her to move you, shake you, take over your spirit and make it soar. It's a decidedly decadent experience. Maryel is jazzing up "Amazing Grace," and you're downing yet another glass of bubbly. Somehow it works. You leave Astor Place feeling a little lighter, transported. Too bad you can only be saved once a week, from noon to 2:30 p.m. on Sunday.