5 weeks out, it's worth looking at the playing field to see whether we can expect a monster wave. Two clear metrics that are somewhat intertwined. First, the race ratings. For our purposes, let's just use Cook. Second, where are the outside groups putting their resources?
Using Cook ratings, there are 39 GOP-held seats that are considered toss-up or worse. That's the meaty part of your map. Sure, there are a couple in the D column already (balanced in part by others in R column), and maybe you dip into Lean R tier, but these are the real trenches. 
So where is the action playing out? Where are the biggest investments happening? And where among these seats have Rs cut bait? As you might expect, the toss-ups are where the action is. But what might surprise you is the stubbornness of "Lean D" seats.
Of the seats that have drawn $10M in outside spending to date, 2 Lean R, 16 are Toss-Ups (15 R-held), 6 Lean D, and 1 is Likely D (Dem-held). The top draws in order:
CO06
VA10
FL26
MN08
MI08
TX07
WA08
All $15M+ slugfests.
CO06
VA10
FL26
MN08
MI08
TX07
WA08
All $15M+ slugfests.
In other words, the battle for 218 is continuing on the turf where it began. The only seats that have been remotely triaged to date are IA01 and PA17. And even in the latter instance, A1A remains on the air. Otherwise, where CLF has pulled money, NRCC remains, and vice versa.
None of this is to say Dems can't run the table (or at least reap a disproportionate share) of the competitive seats, but compared to how things looked even a month ago, this is a razor edge proposition. Not coincidentally, the GB has stabilized back around the D+7 tipping point.
I'd still say this lines up largely with where the models are, but conventional wisdom still may not be baking in the reasonable likelihood of a narrow GOP hold.
Post-script: this analysis is all through September, and with 34 days left, maybe past is prologue. Campaigns themselves are sufficiently well-funded that you'll see surprises. And @DavidMDrucker sees a late deluge of Dem spending not reflected in my notes
