All those grasses spread nicely. I would buy a few pieces of St Augustine (maybe five) for a dollar apiece and place them around in the yard. Keep them watered and fed and they will spread to fill your yard.

If you are willing to do a lot of extra work to make it look nice, then go with bermuda. If you are not willing to do that much work, then go with bahia.

I think the best grass seed is a mixture of fescue and rye. It stays green year round. We buy ours at Home Depot or Lowe's and have never had a problem with weeds in them. Maybe the weed seeds were already in the dirt when you have tried planting the grass seed before. You will have to keep your dogs away from it for a couple of months, until it takes hold well and gets thick. Any sooner and they will be ripping out the new roots. The best time to plant is when the nights are at 50 degrees or above are your thoughts?