I used to have bad wrist aches in my ten first years of playing or so...that was mainly because I tried to play like they teach in the books, i.e. with the thumb in the middle of the neck back and used rather flat fretboards/necks like Jackson/Charvel but still hung my guitar relatively low.
When I begun to have a much more 'rhythm-oriented' grip of the neck, i.e. my thumb is, when chording, extending even over the fretboard at low E, and when playing lead etc. it resides just behind the low E string, plus raised the guitar an inch maybe, they went away without me ever taking notice.
I don't think it's necessary to play with the tips of the fingers, but rather the 'corners' i.e. like 45 degrees from the tip away from the nail, if you know what I mean, and that gives you a much more relaxed wrist position. Also allows for much easier left-hand damping of the strings, which also led me to play much closer to the fretboard than in the beginning, when I pretty much rested my hand on the bridge when playing - now I sometimes pick all the way over the fretboard.
And, I've also created a preference for V shaped guitar necks...I don't mind a thick neck, but I want that thumb to land very close to low E string and V's allow for that.
I have never thought of this in so much detail and it's just my 2c but yeah, my take is that the key to wrist fatigue is to learn to play less with your fingertips and more with the parts nearer to where your fingerprints are centered. There might be a word for that but I'm not native English-speaker and just woke up too, so fill in the word you know what I mean :-)
Dee
"When life's a biatch, be a horny dog"
Amps: Marshall JVM 410H w/ Plexi Cap mod, Choke Mod & Negative Feedback Removal mod, 4x12", Behringer GMX110, Amplitube 3/StealthPedal
Half a dozen custom built/bastardized guitars all with EMG's, mostly 85's, Ibanez Artwood acoustic & Yamaha SGR bass, Epiphone Prophecy SG, Vox Wah, Pitchblack tuner plus assorted pedals, rack gear etc. for home studio use.