My wife and I went to, and enjoyed, both of these places recently. Broadway Diner is in Wintergreen Plaza in Rockville. It's similar to Silver Diner, but I think the food is better; especially the desserts, which are as good as we've seen anywhere. I had the cheeseburger, which is on par with Silver Diner's--that is, excellent. My wife had a shrimp salad platter, which consisted of huge scoops of the salad, potato salad, and cole slaw. She could only eat half of it; we shared the rest for dinner. Our dessert was a super-rich chocolate cheesecake. I don't know if they make their own desserts, but they're impressive.
Tartufo is on Gaither Road in Gaithersburg. It's very good Italian food and quite reasonably priced. Service is good. The bread sticks are a knockout, too.