Have a look at Ruffnuts and Tuffnuts seat covers, made by Allied Seating.
I've got one of each - the Tuffnuts are the 'standard' canvas ones, and the Ruffnuts are made of a special material that is just as wear resistant to canvas, but much more comfortable.
The canvas one is great, and no doubt will outlast my car, but I can't help but feel its a bit rough, tough and agricultural.
The Ruffnuts one on the other hand is soft, comfortable and highly recommended. Allied seating will make them for any vehicle; give them a buzz
Aaron