Let me look into my crystal ball - not!

DEN-LAX-SFO-DFW-DCA-DFW-SFO-DFW-DEN, ~8,618 mi... $300!

It's hard to really address such a multi-segment journey; it could go like greased lightning, it could be delayed by a two hour wait-for-the-gate at DFW. But anyway - 40 minutes at LAX if you arrive on time is not bad, quite doable within the same terminal. One hour changing terminals at DFW is quite doable, using the Skylink going in the right direction. IMO, it's what happens BEFORE that makes a difference, and late summer, late afternoon, things can get stacked up - or not.

Good MR, good price, good luck!