I try to maintain a sugar-free diet regularly, just because. Splenda is a great sugar substitute - measures 1 for 1 same as sugar. Chocolate pudding from scratch, using corn starch vs flour and splenda works well. Any kind of fruit that is on their diet (some diabetics need to watch fruit intake though). Most can be grilled for a different touch. Bryers makes a 'no sugar added' ice cream that is very good. Angel food cake with a drizzle frosting (use splenda vs sugar in the drizzle). Just the ones off the top of my head.
Good luck. And very thoughtful of you.