I believe New Orleans is further than 100 miles from Shreveport but here is the town that I would recommend Natchitoches. Its on the Cane River, it has a lovely historic district, its clean. There are more B&B's in Natchotoches, its a college town.
The film Steel Magnolias was filmed there.
Outstanding resturants one for meat pies and fried green tomatos.
Each Christmas the town for a month is filled with a Christmas theme of lights and activities.
PS is pronunced NAK-a-tish.
My girlfriend stayed a few day's and it was fun taking a carriage ride through the historic district.
I also like Opelousas and St Landry Parish beyond Alexandria about 1.5 hours from Natchitoches. Its closer to Lafayette and in the Cajun Country. Towns such as Eunice, Washington, Grand Coteau are fun.
A small motel in Opelousas under $50 is http://www.OaksMotel.com