Depends where you live. I think Subway is super gross, but being in Austin we have a locally-owned chain called Thundercloud that has similar sandwiches but uses fresh-baked bread and better, healthier ingredients. I like turkey on wheat with avocado spread and lots of veggies - no mayo, mustard, or cheese and I don't miss it because the avocado totally makes it both less dry and more satisfying.
As far as bigger chains, Chick-fil-a can be ok if you have it and don't have any objections to it. Wendy's actually isn't bad if you know what to order (ex: grilled chicken sandwich with no sauce, salad as a side and a lot of times I save my salad as a snack later instead of eating it with my sandwich... I also like their half-size baja salad as long as you leave off the chili and half the tortilla chips.)
I think Panera has some options, but I find it dangerous because pastries. If you have Noodles and Company, they have a few dishes that are under 400 calories in the small size, and then if you add chicken or shrimp they still come in under 500. The bangkok curry in particular is yummy and heavy on the veggies, and only about 430 calories even with a full serving of chicken on it.