Sag Harbor’s Bay Street Theater will be busy this weekend. Tomorrow at 8 p.m., Judy Carmichael and her quartet will perform music from “I Love Being Here With You,” the first all-vocal CD by the virtuoso stride pianist. Ms. Carmichael will sing standards from the Great American Songbook. Tickets are $45 for side seating, $55 for center, while $75 includes admission to an after-party with the artist.