We are always attracted to wool carpets (just go to them without knowing they are wool initially). IMO there is nothing like it but I think that for wall to wall I wouldn't choose it. We have it in our bedroom (Karastan) and it has held up very well for about 20 years but unless you get spots out immediately it is difficult - that is with plain colors. If you have a pattern of course that is different and our wool orientals with patterns never show anything and will last forever! For our side porch we are going with a Karastan nylon. I hope we don't get any outgassing though.

face weight has little to do with 'wear'. Its the twist level thats important. If its a frieze style carpet it won't show any wear as your walking on the sides of the yarn vs the tips of the yarn. Base grade carpet is 26oz so 39 or 46 are substantial upgrades. Carpet is not sold by specs so if your looking for the bigger # must be better. 'Talk to an experienced carpet salesperson who can educate you a bit. If you looking at a box store your not going to get correct info.

Can't really comment on the Shaw, but I can comment on our carpet buying experience when it comes to this style of carpet. Our carpet guy tried to steer us toward the Shaw carpets that compete w/ Smartstrand when DH balked at the SS price (granted, DH hadn't done any research on the carpets or even touched the SS). After feeling the Shaw sample and comparing to the SS, I said absolutely not. Like you we had issues w/ the carpet we put in the last house not being comfortable and stains would reappear a couple days after a steam cleaning & I definitely did not want a repeat on either of those fronts. We went w/ Smartstand and have been very happy with it's performance so far. Super soft luxurious feeling & stains come right out with just a little plain tap water and a clean cloth (even blood splotches from when DS2 cut his foot and tracked quarter sized blood splotches into his bedroom, across the room to his bathroom and back across the beautiful white SS carpet)--AMAZING!! Can you go outside your builder's carpet guy? If you're looking for a better price on SS, try Lowe's. Their price is so low that the local dealers can't touch it--it may even come in less than the Shaw carpets you're looking at. Each dealer's SS has different names assigned to the different weights so you'll need to have the specs to compare apples to apples (i.e. the dealer's SS Intelligent Style is the same as Lowe's SS Lucky Star.) Remember too, that when you deal with the builder's preferred vendors, they like to talk about how you get a builders discount/builders pricing. What they really mean is that the builder will be getting a kickback/referral fee from the vendor for giving him the business. Additionally, the builder may pad the charges from the vendor. All in all, you may come out much better by going through the local Lowe's. Hope this helps!

My husband has been installing carpet for 38 years. For as long as I can remember his advice has always been "100% nylon and stay away from polyester even if the salespeople tell you it's 'better' than it used to be". He installs a good amt of wool carpeting also, in the higher end homes, but it's a very expensive investment. Wears like iron :) Pad depends on the type of carpet but thicker isn't always better.