I was dreamin' when I wrote this. Forgive me if it goes astray.
My rule is to use my first attack on the highest base I think I can 3-star. This means my first attack has been anywhere between their #1 and their #13 (I'm usually in the 8-10 range). I do not wait for anyone else to attack their +5, +10, +whatever. I just go for the highest 3-star, and I usually get it.
What if I'm waiting on a guy that doesn't attack until late in the war - when I'm possibly busy? What if I'm waiting on a guy that ends up not even attacking at all? Both instances are less than appealing for me.
For my second attack, I'll do the same, but I'll wait at least a few hours before hitting again - maybe even several hours. I have zero interest in a honey pot. What I want, however, is to win the war. That happens by getting stars. When I'm ready to play, I (and the clan) deserve to give myself the best chance possible to get three stars. If that means my second attack is in the 20s - which has happened a couple of times, that's perfectly fine by me.
I have never given credence to a +X strategy because it takes away from the decision making process. We have a lot of great attackers in these two clans, and they generally know what kind of base they can level. Of course we all make mistakes, but that's going to happen. We've shown over the last couple of months that - as a group - we can smash our average counterpart. I see no reason to put on handcuffs.
And while this may put the late arrivals in a bind, I'm okay with that. There have been two wars where I didn't have enough time to plan an attack until late Friday. There wasn't much left to hit, but each time I was able to move a couple of 1-starred bases to three - I think they were in the teens. Sure, I missed out on stars, but that's fine. I knew what time the war started and just couldn't make it until near the end. That will happen again this week. Oh well.
The only people I feel for are the super low level guys. If in the first hour of the war, our 38-45 completely wipe out our opponent's 42-50 - because that's as high as they could 3-star, there's nothing left for our 46-50. There's absolutely nothing that can be done. Get there early or just try to win some loot. Of course, with the +X method, this issue exists as well. No idea of how to fix it beyond reserving the lowest bases for them, but that's not a viable option in my opinion.
As far as second attacks, I know I'm in the minority, but I would much prefer everyone to continue to try to 3-star as high as possible. And by the time most are using their second attack, this could mean moving 1- and 2-starred bases to three. The Quest for 150 seems so close and so sweet.
Anyway - short version:
1st attack strategy: Attack the highest base you are pretty sure you can 3-star whenever you have the time to attack
2nd attack strategy: Attack the highest base you are pretty sure you can 3-star whenever you have the time to attack