I used to do a lot of tweaking and micro managing around all the time, but it was driving me crazy, so with certain exceptions, I let AdSense run pretty much as it will. My earnings have increased every year since 2005, so it's worked for me. Lessee, from your list:

My preferred ads units are a 728x90 (that swaps out a 468x60 or a 320x50 depending on viewport of the device), a 300x250 and a 160x600. I rarely change this, although I might change where I put them.

Most of my pages are long enough that I feel I can get away with placing three ad units now, but for ones that aren't, I stick to two ad units or even one. I also use affilate ads, direct ads and Amazon ads on the same pages, if there's room for it and it makes sense.

I tested the 300x600 and it didn't perform too badly, but until Google serves a real collapsible ad unit, I'm not going to run it again - if they only put one text ad in it, it leaves too much white space, specially on a mobile device. I have a lot of mobile traffic.

Enhanced, Expanded and interest based ads run as AdSense default - I don't mess with those settings. Not sure what you mean by Third party ads or social ads, unless you're talking about the ad networks.

Ad Networks - everything but AdWords is blocked. I looked at a LOT of data and as far as I could tell, the 3rd party networks brought in less than ten bucks over the same timeframe that AdWords network brought in mid five figures. That was enough for me.

I block some URLs, probably two categories, and a handful of display ads. Mostly because I don't like em (belly fat ads) or they're not appropriate for the site they appear on.

I use Text and Display, but usually I create separate ad units, one text only and one display only, so I can rotate them at different rates. A lot of my advertisers don't put out their nice travel/vacation display ads until late spring or summer, and those are the ones that do the best for me. The rest of the year, the image ads are kinda meh.

I make heavy use of channels in order to test ad styles and placements. Always looking to mix it up a bit in order to combat ad blindness. Most of my ad units have up to four channels each, and I try not to change them out or rename them, because I suspect (with no way to confirm, mind you) that performance of a channel over time might help keep me from being adversely smart priced. My EPCs are going up and up (even while my CTR is down) but I can't say for sure that the channels have anything to do with it. But just in case, I tend to reuse the ones I have. I also use the targeting options on main channels, so advertisers can find me for placement targeting.

I used to do fantastically well with link units, but they've really gone downhill, and also since Google made some changes to them, they don't work on sites with dark backgrounds (or at least they didn't last time I checked) So I stopped using them almost entirely. I emailed support and asked about it and after a lot of hemming and hawing, they admitted they weren't working properly on dark sites, but said it wasn't a priority for them to fix em. So I took em off.

As far as Google suggestions, whether generic or customized to my sites, I *always* pay close attention to what they suggest, but I don't always implement full or part way. Some of their suggestions have been a total wasted effort, and others have worked out much better than I ever anticipated. My thought is that they have the statistical information I don't, and I know my users like they can't. So it's always worth a consideration, and maybe a test.

I think that covers it.

@netmeg -- great reply!

Yes, I've found in general that mucking around with things too much can be a recipe for insanity. With regard to ad sizes, I too am craving a truly responsive ad unit but have (for the time being) swallowed the candy and use responsive ad switching per Google's example. Of course, this just adds more ad units per slot which makes switching ad type a pain (which I also do occasionally).

Vertical whitespace is a problem for me, even with the 160x600 size so I know what you mean there. Using a colored border can help but at the same time, I prefer to not use borders around my text ads (a subtle choice not often mentioned in relation to ad design/placement).

I can't use horizontal banners as much as I'd like due to dropdowns (a necessary evil I've been able to get less reliant on but not entirely) combined with highly variable page lengths.

The Third Party and Social Ads options are on the Ad Serving tab. Social Ads is essentially about adding Google+ controls to the ad space (in my opinion ugly and not very useful) so I turn that off. The third-party option is a bit less understandable but may not even apply if you have all third party networks blocked (I do this as well).

Your mention of channels is a good extension on this topic. I've used channels for topical groupings extensively but there are many other ways to use as you've eluded to i.e. tracking the effectiveness of color and font settings, page locations, etc. Regarding channels and ad units, I've taken the approach of granularity recently where ad units are concerned. In other words, I make new units for new ad slots so the unit itself tracks location on any given page. I used to do this strictly with channels but despite the extra work, I'm finding it a useful approach where serving responsive ads is concerned.