While not as high maintenance as lawn, your wildflower planting will still require monthly maintenance. And yes, the weeds will definitely come back. You'll have to monitor the situation and remove the weeds either by hand, with herbicide or mowing. I wouldn't plant any grass in it. Especially aggressive spreaders like bermuda or you will go out there one day and find that the wildflowers have become lawn. Wildflowers also require water. Not as much as lawn but in a drought situation, germinating seed and having adequate moisture for that much area is going to be a concern.

If what you were wanting was a substitute for lawn area and that kind of maintenance, I would suggest a nicely laid out planting of ornamental grasses and shrubs to line the driveway and also some trees that will drape over the drive and provide cooling. You can start out with small one gallon sizes or even smaller mail order sizes because that stuff grows fast.

Don't plant bermuda - if you ever want to get rid of it that will be very difficult and require lots of chemicals.

Some of the native grasses like broomsedge will find their way to you. Especially now that seeds are ripening and being dispersed by birds.

Here is a link that might be useful: A weed site, but good pictures of broomsedge