looks like some type of smartweed,

 

@youradrian12
Could be Lady's Thumb which is in the Smartweed family. Dicamba and/or 2,4-D for control

 

Based on your last pic, I only see a few isolated clumps of grass that might be desirable. Looks like mostly weeds within weeds. In areas like that I wouldn't bother with selective herbicides, just hit it all with glypho.
In areas that are mostly good grass with isolated weeds, sure, spot spray with a selective.

If you till up the soil 1-2" you'll probably expose more weed seeds for germination, so you'll want to use something like Tenacity at seed-down to somewhat mitigate the amount of weeds that will come up with your grass seed.

Most people on this forum will tell you that spring seeding is a problematic strategy in general. Not enough time to develop enough to survive summer heat & drought stress. If that area happens to be on the north side of that fence (IOW is in shade for all but 1 or 2 hours a day during summer) it might stand a chance.

Something else to ponder, if it's just that one really bad area then laying some rolls of sod might not be too expensive.

 

Blooms all year round with red/purple/pink grain-like buds. Kills all the grass in the area. Leads to a lack of water drainage after storms in heavy clay soil. I thought it might be creeping something or other - Charlie, Wynonna, Deontrius... My thoughts were: 1. Use a post-emergence pesticide to kill this crap 2. Till the whole yard's soil up 1-2 inches 3. seed and hay around March Thoughts? Thanks!

You might want to research medicinal properties before you bother to throw toxic chemicals on it. Vinegar salt mixture will definitely get rid of it. But but

 

Its either Ladys Thumb or Pennsylvania Smartweed. Its hard to tell the two apart. They're both annuals so a preemergent next spring should prove helpful in controlling it.