Moissac, aside from the cloister, is best enjoyed by exploring a few blocks off the route. Head south from the abbey/cloister toward the canal and further on to the river Tarn. It's far prettier than the chemin along the railroad tracks and there are some good bakeries where you'll find all the usual items plus a variety of small pizzas for the next day's lunch.
I'll second Lectoure. Though it can really shut down after 6 pm, I've enjoyed (overpriced) refreshment at the belvedere square near where you reach the top of the town as you enter after a long steep climb. I've enjoyed dinners at two different restos on the main street and found its cathedral more interesting than most. Bakeries too. It's mid-sized, I suppose, but you can accomplish a lot: I've been to the dentist and gotten a haircut there, and I have good memories of both. Nice people in both pharmacies. In the morning there was a sizeable farmers' market setting up.
Auvillar is a gem. Just trekking through you'll see two obvious sites, the round market and the clock tower, along with the bakery and grocery. Stray a bit and you'll discover a shaded belvedere, a modernized square in front of the local church, a cafe for afternoon refreshment, and dining options. It's a short walk from Moissac, especially if you follow the canal route as most people do, but I've twice found to it impossible not to spend the night.
Most forgettable: Nogaro.
