Like I said, it's impossible to make an informed decision based on the information given, but, all things being equal, the shorter run that pays more will maximize the revenue per mile, and since it delivers Saturday morning, there's at least a chance of getting another load on top of that one before Monday even gets here.
But looking at CPM, you need to look at that in terms of whether or not your time and labor are included in your CPM figure. I pay myself 32 cents per mile, which goes into my CPM figure. It's a good yardstick to measure overall actual net profits with. One load grosses about $150 more than the other one ($199.20 less difference in fuel). Is that $150 worth your time and labor to be on the clock until Monday, or are you actually better off taking the more profitable load and maybe getting a secong load on top of that one? Only your hairdresser knows for sure.
But regardless, let's say you have a CPM of 40 cents per mile (a number picked at relative random, but should be in the ballpark for most vans). One load pays you 70 cents, leaving you a profit margin of 30 cents per mile $220.80 for essentially 8 more hours of driving and 2 days of sitting on the load). The other one pays $1 a mile, leaving you with a profit margin of 60 cents per mile ($189.60 for about 8 hours work). Now you're looking at about a $30 difference in gross profits. Is sitting on the load for two days worth $15 a day to do it, or would you risk that $30 for a chance at another load, and less wear and tear on the van?
More revenue per mile, even on fewer miles (within reason, of course), is usually going to be more in your pocket in the long run. Less wear and tear means fewer opportunities to break down while under load, less time at the repair shop over the life of the van, lots of things.